I would unfortunately say he was probably dangerous.
The few times I have taken a virgin pillion on the back I have been very slow and stopped after a few minutes to check they were happy.
I took a quad out when I rented one on holiday. I used to have a little quad as a kid and we'd have permission from a local farmer to use one of his fields that was no good for him.
Anyway, to cut a long story short I went on holiday with a mate and rented a quad to go exploring in the mountains. I kept to the speed limit,.took the turns slowly and when I checked on him, he was shaking like a crapping dog. Some people aren't wired to enjoy stuff like that I guess.