Sounds fine to me. Pro Shop Guy is in the business of drilling balls and providing advice/tips when asked. If he would have told that guy he couldn't help him, he might have just lost a customer.
Playing devil's advocate, it could be argued that the guy wasn't in his position as "Pro Shop Guy" when giving the advice. At that point, he was just a regular bowler. So his title/job occupation would be irrelevant.
With that said, this is no different than a teammate, who knows your game, giving you advice on making the adjustment needed to run out the game. There is a guy in my league, who also owns/runs a pro shop, and gives advice to his sister (on his team) all the time; he also happens to give advice to those who ask for it, including my teammates when we were bowling his team a couple of weeks ago. It is no different, as everyone in the house could give someone advice; but as mentioned earlier, the bowler has to execute.
BL.