I'm on GitHub/Microsoft's side here. They are not responsible for the content of US export control laws, and they have an incredible amount to lose if they are found to be in violation of US export control laws. Presumably GitHub needs some automated tool to prevent inbound traffic from sanctioned countries, and it's hard to be certain that they are complying with US law if such automated tools have some wiggle room…
https://github.blog/2021-01-05-advancing-developer-freedom-g...