If it's in Ireland ...
I'm not a lawyer, much less a person knowledgeable in constitutional matters and could be simplifying things a bit, but ...
Isn't this an issue where just plain common sense applies?
You see, unless I missed something really important recently, Ireland is still a sovereign state.
I really cannot see what in f*cks' name the US Supreme Court has to do with respect to whatever goes on in Ireland.
Isn't it enough with the crap they deal/have dealt to their own citizens at home?
I think that if the servers are located in Ireland and belong to a company working in Ireland, under Irish law and Irish regulations, I'd say that the servers (and whatever is held inside them) fall exclusively under Irish jurisdiction.
More so if the 'whatever' held in the servers belongs to Irish citizens.
All this unless some Irish court decides otherwise (which I think is a bit of a strech) or there's already a provision in place for events such as this.
It's not impossible, strange things happen these days.
It could also be that MS backs up their overseas servers in US facilities and this is so, then it would seem to be another matter altogether.
Cheers.