First a question about his catching. He’s a 2020. It’s July 9th. How many D1 catching offers does he have so far? Or how close do you genuinely feel (not hope) he is to D1 offers? How many more events does he have this summer?
The later it gets in the recruiting cycle (and into the fall) the more likely it is to be recruited as a pitcher than a position player. Teams are more likely to be looking for one more pitcher than one more position player (even understanding catcher is a unique position).
If the pitching camp isn’t that expensive why not attend? It’s hard to say how interested the coach is from a post. Only you know. How does this coach’s interest in your son as a pitcher measure up to the D1 interest that hasn’t turned into a D1 offer.
Also, there’s no shame in playing D2 or D3. A player should look for the best opportunity that provides a quality education and baseball experience. It’s more fun to start D2 than watch D1 ball from the bench and ultimately transfer.