He started as a volunteer, but nowadays he does get paid. From him himself:
I'd like to correct a misconception that I keep bumping into before it becomes too widespread:
While most of the patches I've posted to date were done on a free-time/voluntary basis, theymos and I did recently come to an arrangement, and I am now paid for the work I do on Bitcointalk.
Took back my words after reading your quote - he earned whatever he's getting and this is only the start..
Why spend more Bitcoin on third-party developers when we already have our own wizard, PowerGlove, doing everything for free? If anyone needed to be paid to enhance the forum, it would be him. He made significant patches for free; imagine what he'd do if paid.