Greenglass clearly was a guy influenced by his older sister and brother in law and the times. But he knew enough that he wanted to live here. He sounded to me like a guy who with a different set of relatives/friends would never have been involved in such acts.
The Rosenbergs on the other hand were true believers in what turned out to be a criminal form of government. Many if not most knew by the 1940s but some did not and the USSR was a US ally in name so it is easy to why the Rosenbergs existed at that point in US history.
It amazing that anyone would still defend giving atomic secrets to Stalin or Hitler or Saddam etc. The children should just be happy the USSR never used those weapons making their parents just slightly less evil.
Hard to know what they were thinking, isn't it? From 1920 until most of them were dead in 1933, ethnic Germans wrote to their relatives in the United States about the Holodomor. German newspapers in the midwest printed the letters (The University of South Dakota has
reprinted them and has the newspapers archived). In addition, Gareth Jones, Malcolm Muggeridge and Eugene Lyons, among others, wrote hundreds of accounts before 1934 of the mass murder taking place (full texts archived
here). Anyone who wanted to know, knew.