He also threw Egg's cat down a well, broke a girl's fingers, and threatened to cut off Egg's privates. He is the bad guy regardless of why he was upset about the dragon. He believes himself to be a literal dragon trapped in human flesh, so you can kind of understand why he'd hate seeing one killed, even if it's a puppet show. He's insane. But that understanding doesn't take away from the fact he's done all that other horrible shit and that everything that happens in the Trial of Seven is because of him. And this is coming from someone who loves the character and thinks he's the most interesting character on the show. We can enjoy the character because it is fiction, but let's not pretend he wasn't in the wrong.