56harrisond

If there's no touching then I don't see the point. Without the interaction it would get old pretty quickly I suspect. 

My muscle worship experiences have all been very interactive and hands-on 

One provider I see operates a yoga studio. So clients pay for a yoga session, and any additional cash exchanged (as a tip) is up to him to declare -or not.

He’s a professional (or is supposed to be). He shouldn’t need to know why, nor should he be chasing you for business. It’s not like he’s being faithful to you is it…so why should it work that you only hire him?
I don’t think it right that you should treat it like a relationship break up: “Hey!…I met a younger, hotter guy. I’m just trying him out but if he isn’t up to  the mark then I might come back to you…but only if you get your act together on X Y and Z. Have a great day”. Hmmmm …no, that doesn’t sound good however you phrase it. 
Just tell him you’re not hiring right now. If he’s wise he’ll understand why. If he doesn’t understand why then you can be sure that any explanation by you wouldn’t have landed well, and would have surely jeopardised the chances of any future sessions being pleasant.