It's true that there are some loopholes [1]. It's also true that as a permanent resident, you come under the category "US person", which some/most of the ITER law refers to, which restricts non US-persons from working with "Spacecraft Systems and Associated Equipment" [2].

But I think it's fair summary to say that if you are neither a citizen or a permanent resident, you have a damn tough hill to climb [3].

[1] https://www.quora.com/How-can-non-U-S-citizens-work-for-NASA...

[2] https://en.wikipedia.org/wiki/International_Traffic_in_Arms_...

[3] https://www.inverse.com/article/21487-elon-musk-spacex-forei...