Riker's insubordination was crazy, it's the reason why I can't grade this two parter highly. It was like his first day on duty.
I guess I can sort of see why someone might feel that way, but personally, I don't see it falling completely out of the realm of possibility for him. He's always been something of an egotistical, pompous windbag, & once he gets his mind set, he's often quite stubborn. A slip up like this might be possible if he let it get away from him, which he clearly did