> The issue is, if we're going to do this heavy lifting anyway, might we do it in a way that doesn't involve theft ?

Expropriation usually involves paying the owners so it isn't theft, its just the government buying out the stocks just like a private corporation would. Are you saying Elon musk stole twitter? That is the same thing.

Anyway, here since this is shared between countries its better to just regulate what these processors can do, like the EU does when they regulate how large payment processing fees can be etc. Since its used for international trade no single country can own it.