Well, if the Ministry manages to find him all the way out here he's probably going to end up in Azkaban anyway. How much more damage can he do?

"Oh... I guess I should tell you-I'm a wizard. Underaged wizards aren't allowed to do magic outside of school and I lost control of mine when Aunt Marge said what she did. I started thinking about what she'd look like swelled up like a balloon and then she was a balloon. And then I left." He was not about to wait for the ministry to either expel him or arrest him. And he certainly wasn't going to hang around to see how mad he'd made his Uncle. He's guessing very.

"And then I ended up here so I don't know if anyone's managed to get her down."