Kicked out is a bit hyperbole. They don't have their champion anymore but the deal and their minority ownership stake are inked. They still get tech and profits. They might not have a path to owning OpenAI now but that was a problem a few years down the road. They can also invest in Altmans new thing and poach OpenAI talent to bolster their internal AI research which is probably going to get a massive funding boost.
The PR hit will be bad for a few days. Good time to buy MS stock on discount but this won't matter in a year or two.