So, what's Sanji's mental block? Could it be that he fears becoming like his father, since that was his first exposure to what a king or conqueror is? He suppresses that part of himself because he's afraid he might end up like Judge, someone who conquers through fear and oppression, believing his royal blood makes him superior to everyone who doesn't share it. Maybe Sanji will eventually realize that he can become a king without becoming Judge. I doubt his mental block has anything to do with hitting women, that's definitely not it.