Or the scientists and engineers themselves are wanting out of the US and were offered secret offers to "dissapear" and live elsewhere under a new identity

>to protect themselves from America.

not necessarily from America. The goal #1 of the US dominated NATO for example was to prevent Germany from getting nuclear weapons in exchange for protection by US. Now with US de-facto withdrawing, Germany would have to quickly get nukes (as well as missiles to carry them) - i don't see other option for Germany here giving the environment in Europe and MidEast. So they would also need such scientists. South Korea, Japan, Australia seem to be in the similar situation too. (and everybody understands that a nuclear weapons program can't be a long multi-year endeavor - somebody will try to stop you - and so it must be very fast once started, and thus you have to have ready-to-use skills and knowledge)