Every public communication is propaganda, that is the point being made (which you missed). The difference between good or bad propaganda are the goals.

For example: Propaganda for higher wages and polical participation? Good.

Propaganda for wage depression and chauvinism of any kind? Bad.

Which brings us to your post: Most soviet propaganda indeed was of the good kind. While most american propaganda indeed is of the bad one.

Every public communication is propaganda, politcal content is irelevant. It depends on the goals of said proaganda if it is bad or not.

If you compre both events beyong the absolute surface you might find the difference:

The soviets kept them under lock and key, extracted their knowledge and then got rid of them.

The US gave them high paying jobs, citizenship, honored their work after they passed, and amnesty for their crimes.