When you look at his profile, he's not tagged as a Professional but he has a Custom Title attribute whose value is Professional.
If you search all Pro users, he doesn't appear in the result list.
Yes, I did do that and saw he is not a member of a Primary Group so should just appear as 'Auto Puzzler' (which is what it says when you're a Rookie) but even if he has given himself the title Professional it shouldn't appear in that position!
Odd indeed; you will also notice he joined in April 2009 but this is his first post! Maybe he just pops in and out from time to time..
A good solve though!
Edit:
OK, I've been into his profile and taken out the 'Professional' as it was somewhat confusing.
He's back to being a Rookie now and on his way to his first point!
I was wrong to say it should just say 'Auto Puzzler' on the status line however; as a Rookie that line would be just be empty, so I've written in 'Auto Puzzler'.