Sounds like a sort of compromise between full lessons (maybe a bit dull to the pro) and simply gambling with him for very cheap (maybe a bit dull to the player if he can't win).
I guess for 20 bucks, you get a little instruction, and the pro gets a little practice/fun.
I gotta say though, I think a lot of guys have this magical thinking about pros, as if being in the same room with them causes some pro pixie dust to rub off and improve your game. They almost act like they'd jump at the chance to pay even if they didn't get a single pointer.
But how does that help anything? There's no bet or tournament so you aren't learning how to play under pressure. You get to watch what he does, but you can watch what TWO pros do in a youtube match for free. And you get to play a little, but you can play a little with other people or alone or just the nearest better shooter. Honestly when you're at the table it should be irrelevant who the guy in the chair is.
So, my answer is... maybe, but only if I get that Q&A session after the rack.
Or preferably, I can stop and ask anytime in the middle of the game "what would you do here?"
That part alone is what I would pay for.