I think Jon really, really enjoys watching other people have sex. Has no desire to personally involve himself in the process, really, would much prefer nobody else even knew he was watching at all. Watching porn is nice enough, but it’s not quite the same. A not uncommon sexual fantasy for him is walking in on other people having sex, and they’re all too distracted to notice his presence so he hides himself in a corner and just watches them. Sometimes it combines with the rape kink and they catch him in the act and punish him for watching them, but sometimes they finish and leave without noticing him rutting against his hand in the corner.