He's not going to just walk away from $11M.
He doesn't have to. A buyout is not so bad from the player's perspective, he'll get paid a significant amount up front, and he'll be free to earn whatever teams will give him. Drouin, even at his best, is probably not worth what MB signed him for, but if he gets bought out and signs for half that in a lower pressure market he'll probably end up with more money overall in a role that he can do well in.
I don't see why the habs would buy him out. Either let him do LTIR or let him prove he can play and keep or trade him. It's not like he stunk last year, he started off fine and dropped off a cliff. He's proven he can play a certain role, at times, the habs should try to obtain value for that.