The Digital Markets Act and/or Digital Services Act ought to have something to say about this, especially the "this secret decision is final and we refuse to say anything else" part of the story.
That wording sounds like the decision was made in Israel and not the US.
I would guess the shutdown requests came from Israeli security services. Thus it is final and not appealable and can also the reasoning can not be revealed.
Microsoft have to choose whether to operate in the EU. There's been a long struggle between conflicting rules of US unaccountable intelligence access vs. EU privacy law ("safe harbour") that is relevant here. https://blogs.microsoft.com/on-the-issues/2015/10/06/a-messa...
Honestly, the day may come when some US corporations decide operating in the EU is more trouble than it's worth. I don't really expect that--it's a big market--but it could happen.
Naturally — one cannot be a servant of two masters, and some US legislation does at least seem to be incompatible with EU legislation: https://en.wikipedia.org/wiki/Max_Schrems
Same is of course true for Chinese companies deciding to not bother operating in the USA, or UK companies deciding it's not worth the effort to operate in Argentina.
But it's not likely to be a big deal if it does, because software … how can I put this?
The saying goes "the first 90% takes half the time, the second 90% takes another half of the time, the third 90% puts you over-budget", etc. but that same effect also means it's easy to catch up most of the value even with something relatively mediocre.
The combined armies of every member state of the EU, if it came to that.
Well before that point, they can just go through a normal court process because the EU has been empowered by the governments of each member state to write such legislation.
The decision might just as well have been taken place on the moon, laws such as DSA, DMA, and GDPR tend to protect the resident and rarely cares where a decision affecting that resident was taken.
