I agree, Spiderman and a motion simulators like Body Wars are not the same thing. Motion simulators make me sick, they're the only ride that does this. They trick the brain into thinking your moving and you get qweezy if you have food in your stomach. BGT used to have that simulator next to Montu, I rode it near the end of the day and I came off it feeling tired and dizzy. Back to the Future at Universal also does this. I don't like motion simulators.
Spiderman is completely different. Sure, the car spins around, but you are moving, whereas in a simulator, they are tricking you by shaking the entire simulator. And the scenes where you are falling down the side of the building are so realistic, it seems like you're actually falling. You don't get sick on Spiderman like you do on a motion simulator because it's so real. The car doesn't tilt from side to side like a simulator, I think this has a lot to do with it.
Tell him to ride it, he won't get sick. If not then he'll change his mind when you come running out of the exit yelling how great it was.