Most contracts also have a clause that a breach of one part does not invalidate the remainder. There are elements that typically out live the end of a contract as well, often the poaching and non-compete clause
One could argue that firing the Loopt founder guy who was an at-will employee isn't a material event invalidating a contract unless the contract specifies exactly that.
Really? I'm a lawyer, and I can't even see an argument of how firing a CEO would affect investment agreements at all unless Microsoft specifically conditioned their investment on Altman remaining CEO forever.
No matter how smart or dumb that move was.