Hanna Björk wrote:
Having training in martial arts does not make other people responsible for your irrational overreaction when startled.
Since we do not know the whole story I would hardly call his reaction an "irrational overation" by any means.
He was in his home alone for all he knew. It was clearly stated no one else was supposed to be there. Then he is for all intents and purposes "attacked from behind". He responded just as his training indicated he should and defended himself with reasonable force.
Maybe this could also be a lesson to all of the girlfriends, boyfriends, and spouses out there who think it is cute to kick, punch, slap, etc at their significant others who train in martial arts. Attacking someone who isn't expecting it can lead to a natural reflex reaction which may lead to your getting hurt.