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...