So, what exactly is the problem here? No, this isn't what I'd call an ideal classroom situation by any stretch, but I didn't see any "violence". Unless there's something missing here, I don't see how this merits resigning.
Oh, I know someone will say "You never touch kids", as if we're supposed to marvel at that statement and agree in awe. Handshakes, pats on the back, a hand on the shoulder as you scoot behind someone in a crowded aisle--we touch kids all the time, and it's quite innocent. So I need something more than "You never touch kids" to explain why this guy felt the need to resign.