So importantly, what's the reason they would do any of this? Curb competition? Don't make me laugh. User-wise the entire fediverse is so tiny compared to meta none of their metrics would even be able to show us due to rounding.

Is it really so difficult to assert that their only valid motivation could be to preempt EU legislation by talking about how they're embracing open tech? And how completely blocking them would actually play into their narrative by allowing them to argue how useless trying to force big tech to be open is, clearly no one wants that's they tried?

It's a symbolic piece for them. If we can use that to lure users away from Meta all the better, but even there be real, the total amount lured might be relevant for AP but unnoticeable to Meta.