There is no such thing as "5th column citizens". This was Ottoman Turkish propaganda to portray the entire Armenian race as a rebellious belligerent and justify rounding up farmers and peasants for death marches and ethnic cleansing.

German vice consul Max Erwin von Scheubner-Richter who was in the Ottoman empire described how small acts of Armenian self-defense were portrayed as large rebellions and for what purpose:

I have conducted a series of conversations with competent and influential Turkish personages, and these are my impressions: A large segment of the Ittihadist [Young Turk] party maintains the viewpoint that the Turkish empire should be based only on the principle of Islam and Pan-Turkism. Its non-Muslim and non-Turkish inhabitants should either be forcibly islamized, or otherwise they ought to be destroyed. These gentlemen believe that the time is propitious for the realization of this plan. The first item on this agenda concerns the liquidation of the Armenians. Ittihad will dangle before the Allies a specter of an alleged revolution prepared by the Armenian Dashnak party. Moreover, local incidents of social unrest and acts of Armenian self defense will deliberately be provoked and inflated and will be used as pretexts to effect the deportations. Once en route, however, the convoys will be attacked and exterminated by Kurdish and Turkish brigands, and in part by gendarmes, who will be instigated for that purpose by Ittihad.

A lot of Armenians in the Russian empire (Armenia was split between the Russians and Ottomans) joined the Russian army because they were conscripted. Same as many Armenians in the Ottoman empire joined the Ottoman army because they were conscripted. These soldiers would be murdered by the state they were fighting for when the genocide began.

Armenian massacres had been taking place increasingly in the Ottoman empire for the past century. The Sultan created the Hamidiye, which were armed irregulars that were allowed to pillage and slaughter Armenian villages without restraint. The Ottomans tried to ethnically cleanse the Armenians much earlier during the Hamidian massacres, which killed 300,000 Armenians until the great powers told the Ottomans to stop. With the world war, they were now preoccupied and the Ottomans decided to try again.

Because it had already been open season on Armenians for a long time, there were already Armenian resistance fighters called fedayi who were the only ones guaranteeing the protection of the Armenian population. A lot of them volunteered to fight with the Russian army because they wanted to free the Armenian nation from an oppressive and despotic imperial government set on eliminating them.

This is similar to the Polish Legions that fought both the Russians under Austria and the Germans under France at the same time. Evidently, the Russians and Germans should've been rounding up those traitorous Poles. But why would they round up all these non-combatant civilians that aren't even a threat you probably ask? Well, that's the same question you should be asking for Armenians. Don't ask "how true is it" as if the Armenians (again, "the Armenians" isn't a belligerent) had done something wrong. Killing Armenians doesn't justify killing more Armenians.

You seem to be a Slovak. Should Austria have killed all the Slovaks that wanted independence? The Slovaks weren't even being killed and the Habsburgs were handing out more and more autonomy.

Most Armenians fought with Russia. There were 150,000 Armenians that were conscripted in Russia and 50,000 Armenians volunteers from both the Ottoman and Russian empires. The rest of Armenians fighting in the war are small by comparison. 900 Armenian students studying in France joined the French army, and 850 of them died at Verdun. The French Armenian Legion in the Middle East fought with the French and British against the Ottomans. General Allenby praised them for making his victory possible.