people act in their own self interest, that doesn't mean self interest is simple

Maybe North Korea offers them more money?

Maybe Russia has a backdoor deal to have their scientists develop something 'for russia' that people know goes out the backdoor to

Maybe Russia forces them to work on things or they will hurt their families.

Maybe Russia won't let them leave and they are going to do worse things for money unless we keep them employed.

Maybe they hate the US and want to work for their enemies

HN often gets very reductive on why people make the decisions they do. Especially when those are related to decisions made by 'traditional' companies and state actors. Lets not assume that the entirety of the US state department and ULA aren't well informed about the decisions they are making.