Can't help but feel it was Altman that struck first. MS effectively Nokia-ed OpenAI - i.e. buyout executives within the organization and have them push the organization towards making deals with MS, giving MS a measure of control over said organization - even if not in writing, they achieve some political control.
Bought-out executives eventually join MS after their work is done or in this case, they get fired.
A variant of Embrace, Extend, Extinguish. Guess the OpenAI we knew, was going to die one way or another the moment they accepted MS's money.