[skissane]

It seems rather silly to me to worry about the knowledge of a few UK citizen SpaceX engineers, in the event of a hypothetical US-UK breakup, considering how much information the US and the UK already share in the fields of nuclear weapons and SIGINT. Surely knowledge about the later two is a much bigger concern than the first? Yet, if they are willing to risk the later, why not risk the former as well?

Besides that, the risk of a US-UK breakup has always appeared to be low, and Brexit arguably makes it even less likely.