This is an excellent question because if you asked the various members of many of the left-wing German terror groups of the late 60s and 70s, they would forcefully argue that they were a reaction to to their parents' embrace of Nazism and anti-antisemitism. Unfortunately often their actions call to mind the old adage: If it walks like a duck, and talks like a ducks... it's probably a duck. Though as I will explain at the end; Mahler's flavor of antisemitism seems to have very little in common with that of his comrades in the 60s and 70s.

Generally regarded as the most important predicating event for left wing radical groups and terror groups in Germany was the June 2nd 1967 student protests in Berlin against the visit by the Shah of Iran. The protests turned violent as the Berlin police boxed in the protesters and beat them, and allowed Iranians and some Savak agents to hit and maim protesters as well. Ultimately a pacifist theology student named Benno Ohnesorg was shot by a Berlin cop while in custody, creating the first true martyr of the burgeoning movement.

After the protesters were dispersed, many headed over to the Ku-damn headquarters of the Berlin SDS office (the SDS in Germany was unrelated to the American Students for a Democratic Society, but served much the same function in West Germany). A young mother, Gudrun Ensslin, had attended the protest and later at the SDS office she screamed to the assembled crowd "This is the Aushwitz Generation! We must answer violence with violence!" Ensslin would, in short order, co-found the so-called Baader-Meinhof Gang with Horst Mahler and her boyfriend Andreas Baader (their true name, of course, was the Red Army Faction).

Essentially the Red Army Faction believed that their parents' generation, the Nazi Generation, had a lot to answer for in their crimes. And further they believed that the German state was still utterly full of former Nazis and formed a hidden fascist underbelly that needed to be rooted out. To an extent they were correct; the amount of former Nazis running German society and industry was almost absolute. However there is little evidence of a massive fascist underbelly shaping West Germany in the late 1960s.

It would be fair to say that many of the radicals couched their feelings towards Jews as anti-Zionism. Essentially "we don't have any issues with the Jewish people, just those awful Zionists in Israel ruining things for others in the middle east."

This attitude led the members of the burgeoning Red Army Faction to travel to Jordan in May of 1970 to undergo training at a camp run by the PFLP-GC (a mostly Marxist offshoot of the Popular Front for the Liberation of Palestine; which was dedicated to destructive acts against Israel). The Germans clearly had different goals than their Arab comrades (the RAF's goal was to attack the German state and their American allies, causing the German state to respond with such overwhelming force that the population would rise up in anger to attack it, and thus usher in a glorious socialist revolution... ahh the sixties). But they certainly found a common cause in their revolutionary and leftist ideals; and this lead to collaboration, the providing of weaponry, and more.

The most famous, and infamous examples of this is the hijacking of an Air France passenger plane and hostage taking in Entebbe, Uganda. The attacks were carried out by members of the PFLP-External Operations (yet another offshoot) and members of the German Revolutionary Cells. Notoriously, when the passengers were being taken off the plane at Entebbe, they were separated out between Jews and Gentiles. Famously as they were being separated, one of of the passengers, an Auschwitz survivor, pulled up his sleeve and showed Wilfred Boese, one of the German terrorists, his camp tattoo. Boese supposedly replied, "But I'm no Nazi, I'm an idealist!"

While there is some debate about the accuracy of this anecdote, it absolutely perfectly captures the thought process of many of the German terrorists who prided themselves on their commitment to the intellectual theory behind their praxis. "I can't be a Nazi like my parents because I've thought all of this through intellectually!" If it walk like a duck...

Of note is also the story of Hans-Joachim Klein. He was a member of the Revolutionary Cells recruited by Carlos the Jackal to overwhelm and Opec Minister conference in Vienna in 1975. He was shot during the raid and though he and the other raiders escaped. During his recovery Carlos tried to recruit him to participate in the coming Air France hijacking that ended at Entebbe. But by this point Klein was beginning to have serious second thoughts about the anti-Semitic basis of the plan and much of the other efforts of his comrades. You see Klein's mother was imprisoned at the Ravensbruck concentration camp, and committed suicide shortly after Klein's birth two years after the war ended. It's unclear whether his mother was, in fact, Jewish; but Klein certainly believed she was. (She had been imprisoned for "Rassenschande" which basically means "racial discrace" and likely meant in this case either having a close relationship, or sexual relationship, with a non-Aryan).

Klein was able to successfully beg off participation in the hijacking, and afterwards decided to fully break with his past by sending a letter to Der Spiegel "renouncing his terrorist past, and providing a warning to two German Jewish leaders that there were active assassination plans against them in the works by members of the German Revolutionary Cells.

Far and away the best source of information exploring the issue of West German radicals and their relation to antisemitism is "Utopia Or Auschwitz: Germany's 1968 Generation and the Holocaust" by Hans Kundnani. It is masterful.

Oh and a note about Horst Mahler. I'm not sure you can fully link his particular antisemitism to the idealist, "but I really only hate Zionism" of many of his comrades.

He is an absolute odd duck. He was much older than the folks in their late teens and early twenties that made up the burgeoning RAF. He could be comically inept (once, before the group became active, Andreas Baader had been arrested for some offense. Because he gave a false name, the police didn't know who they had in their custody until Mahler, a lawyer, showed up and demanded to see "herr Baader.") He was also not well-liked by his comrades (actually fairly actively loathed by many of them).

In the end he was captured quickly after the founding of the group and was ultimately excommunicated from the group for writing a group manifesto that the others fully rejected. After serving his jail sentence he slowly began aligning himself to pretty virulent antisemitic groups including groups dedicated to Holocaust denial. He ended up serving several long prison sentences for his antisemitic pronouncements (which is illegal in Germany). One of which involved him saying "heil Hitler" and giving the Nazi salute to a Vanity Fair reporter interviewing him about the beginnings of the RAF.

I think pretty much all of his former comrades on the left would absolutely reject his belief system; regardless of their own feelings about Zionism, etc.