tunalegs
Pretended Artist
When a "pro" photographer or whatever offers up quality work for free it takes away some of the market or diminishes bargaining power for those who want to be paid for their images.
Except of course putting photos on flickr isn't really giving photos away for free. If this guy were going in to a job and saying "you know what, don't pay me, because the exposure is payment enough" - then he'd be diminishing the power of other photographers to get paid.