PiedmontChun
Purple Belt
To me it still sounds like you're just upset you got beat by a beginner. You're upset because a guy went for a submission.....that's the truth of it. Okay he was doing it wrong but he's beginner he's not going to do perfect technique. You say you don't trust him....um pal he's rolling you're rolling accidents happen that's bjj for you get over it. If he held on a submission after you tapped or punched you in the face or dug his elbow into your face that would be bad but if a beginner goes for a submission....well that's what he's meant to do, fair play to him for giving it a go and not being timid your fault for not defending it or escaping.
Bjj rolling is different to sparring because in sparring someone goes hard you've got to take it and it'll hurt if hit. In bjj anything hurts you can quit straight away. That's the good thing about bjj you can go hard without as much risk of injury
Dude, I need my limbs / joints for other hobbies and life in general. Granted a face choke isn't putting me in real danger, but other submissions can if you put it on 100% right out of the gate. I don't roll like it is life and death.