There seems to be a faction of people that think it is a good thing i.e. sensei locked me so hard that coudn;t train for a week, what a poweful guy.
powerful? I think not... what did you learn in that encounter? you were in a vunerable position, we give our minds and bodies in practice, we trust our teacher, he went too far, when he didn't need to. In my eyes, that is just wrong. It is possible to pin someone without damage, so why damage?
now i believe in hard training but when you are giving your joints to someone there should be an element of trust and it seems to me there are instuctors out there that abuse that trust and have set up what amounts to abusive relationships with most of his students.the sensei that threw a small young beginner female, who cleary wanted to gain confidence and fitness by doing a softer marital art, so hard that she bounced and took pleasure in making poeple scream i watched in disgust and will never train with agian
sorry for the rant,
he may well have damaged the confidence of the young beginner, what sort of teacher is that?
Teachers are there to build confidence, strength and skill. He sounds to me like an ego bound bully (from what you have said). Find someone better...there are many out there.
On my recent trip around the west coast of the USA, there were a couple of names that kept cropping up, that had a reputation for the type of behaviour that you describe. I just avoided them and found other good teachers to visit.
good luck in your search and your training.