Well that is the problem, the damage is done the institutions and businesses relocated or are relocating and everybody spend billions severing ties.
At this point the UK isn‘t a large and affluent trading partner any more. So why would you give a nobody anything special?
Also the EU is power centric and the UK embarrassed themselves worldwide. Why would you want somebody like that on your team?
You can just let them bleed out and talk about them rejoining the team when their pride is broken and they are lit. begging you to rejoin.
That is not rly correct. They provide the source code if you subscribe which is enough to honor GPL. The part about not distributing the code and not building a fork / competitor is against the GPL. GPL would even be honored if they print out the code and sent it to you per mail after you asked for the code. GPL does not mean you have to host the code on a public site.