Most Helpful Guy
When you say stop, you're taking control. I think he likes it. Order him to do stuff, toy with him and watch his reaction. I bet he's gonna like it. He might have a taste for the sub role. It might be a big step for me to make of course, but if you explore, you'll know for sure.
Most Helpful Girl
It's the tickling/foreplay that turns him on, not saying stop or no.
But, if you must know, you're going to have to ask him.