Well if he does then it will all be on him. If he's smart and he's listening to the people he'll let Congress have the final say. Personally I get the feeling he'd rather not go to war but is having to cave into the hawks because of his statement about chemical warfare being a game changer and then later a red line. I'm betting he wishes he could take all that back right now so as to not feel so pressured to live up to his word.
This person is a complete alien to you. The way he thinks can't be imagined by you. That's a projection of yourself.
He's a decent actor. Although, he is riding on a lifetime of brainwashing and a lot of powerful technology.
He doesn't have to live up to anything, because he doesn't make any of the important decisions. Creatures of power are running this shipwreck.