Like the board presumably called her and said, "hey Sam is out, you're the CEO for now, more details to come"
And then in the next 48 hours she had a chance to talk to Sam and others and realize that she was on his side.
I wouldn’t take over as CEO or interim-CEO unless I knew why the previous CEO was fired and was OK with the process and reasoning.
Like the board presumably called her and said, "hey Sam is out, you're the CEO for now, more details to come"
And then in the next 48 hours she had a chance to talk to Sam and others and realize that she was on his side.