Well.. this certainly must be a very embarrassing situation for him, poor guy. Most people are smart enough to immediately realize he has been hacked though.
EDIT: They appeared to have deleted his account..
Twitter usually deactivates or locks out compromised accounts if the victim can prove their identity; that doesn't seem to be the case here. The hacker is still tweeting under @jonmatonis. As I write this, there are two tweets:
Jon Matonis @jonmatonis 1h
Good luck getting your Twitter back now Jon. Shouldn't have ignored me, GG.
Jon Matonis @jonmatonis 1h
@octal He got his other stuff back...
Ah, very true my mistake. It seems they managed to steal his twitter handle though. At least they no longer have access to his followers.