I think a lot of people are ignoring MS. It does seem more like an I'll judged emotional outburst than a reasoned reaction. The competition authority in the UK is well respected so their conclusion is going to be given great weight by the EU and the US. Given the EUs track record, they're likely to be stricter than the UK, so the CMA adjudication is a good forward indicator that the deal is basically dead.
Given that it wasn't even the UK government who made the call here that probably won't achieve much. Would the UK government really change the fundamental rules of the game to override the CMA just because the regulator did its job? Doesn't seem likely. Literally all of the commentary I've seen about this from any source not connected to Microsoft or Activision is taking the view that it was the right call by the regulator.