>>6496696That's someone that was born without a dick, though. Someone that's used to having a dick will generally get neurologically set into traditional masturbation for orgasm, and will have a hard time getting of to other stimulus if they aren't able to jerk off, whether it be due to physical restraint, lack of permission, or (in this case) absence of a dick to grab. They can retrain their brain to get off to other stimulus (nipple action, rubbing their removal scar, anal play, or even mouth play if they can see the mouth as erogenous), but getting your brain out of one erotic rut and making it make another rut for itself is a real pain in the ass, and it takes a lot of focus and dedication.
Of course, if you're the one missing your dick, can't get off without it, and you're being kept in a cage with someone you wanna get freaky with, what else are you gonna do with your time?