He wasn't anticipating a hippo. Who the hell anticipates a girl turning into a hippo? But he's used to all kinds of quirks so it doesn't throw him off. It just surprises him.

He lets her chomp and slash her way through, while he finds a weapon to use. A sturdy branch will do the trick. Just keep swinging!

He sure misses his quirk though. He'll have to ask her what she knows about it being missing when they finish here.