I recently read an excellent biography of theoretical physicist and director of the Manhattan project Robert J. Oppenheimer American Prometheus. The book extensively details the leftist connections of many of the atomic scientists who worked on the bomb, including Oppenheimer and his brother. It also explains many of the scientists had mixed views on using the bomb on Japan and on the emerging Cold War. Some scientists even proposed to Oppenheimer a plan to convey nuclear secrets to the Soviet Union in violation of their security clearances in order to prevent a nuclear first strike by the US, because of this Oppenheimer later had his security clearance revoked. Considering many of the atomic scientists who worked on the bomb had leftist sympathies and doubts by the emerging nuclear arms race, especially after Hiroshima and Nagasaki, what were their reactions to the execution of Julius and Ethel Rosenberg for allegedly conveying nuclear secrets to the USSR? Were those who advocated sharing the plans for the bomb during the war sympathetic to their decision? Or did the Cold War change the views of those who originally dissented against US nuclear policy?
I don't know of any systematic survey of how the Manhattan Project veterans thought about the Rosenbergs. For a few we know they, like many on the American left at the time, thought the charges were trumped up. Philip Morrison clearly falls into this category and was involved in the later appeal for co-defendant Morton Sobell, arguing that the information that Greenglass said he gave away was useless from a technical perspective.
By and large though there was silence on the subject. The premise of your question, that they might have identified with the Rosenbergs and their impulse to espionage, seems totally unlikely to me. Rosenberg was not a scientist, and neither was Greenglass, his brother in law who was the spy at Los Alamos. They did not give away the information as part of a broader plan to make the world safer or anything like that. They were Stalinists, plain and simple. And of course the Rosenbergs went to the grave denying they had done any such thing, so there has never been any way to "identify" with their beliefs, whatever they were. (I have written about this here.)
The more interesting question is how they felt about Klaus Fuchs. Fuchs was a scientist and a peer of theirs, someone they trusted. They literally used him as a babysitter during the war. His technical merits were impressive and he was core to the weapon design enterprise, having worked on the initiator, implosion waves, and was the co-holder of the patent on gaseous diffusion enrichment of uranium. So no minor figure. Many of them knew him personally and considered him a friend.
The main sentiment from those who were friendly with Fuchs, if they said anything, was that they were shocked and wanted to emphasize that even though he was a spy, he also worked very hard for the US and the UK. That is, they wanted to emphasize that he was not working against the US-UK just because he was also working for the USSR. This sentiment was said publicly at the time by no less than Hans Bethe, for example.
In terms of whether anyone said publicly that they supported the spirit of espionage after the fact — definitely not. For reasons quite obvious, I think; this was the time of McCarthyism. I have never seen anything that Oppenheimer ever said that would seem to be supportive of spying.
Those (like Oppenheimer) who wanted to end the idea of the "secret" of the atomic bomb were doing so in the service of a broader system of international control of nuclear weapons. What they wanted was an orderly disarmament and commitment to no further development. Not a secret arms race — the latter was what they feared most of all.