I generally agree with 62des. It shouldn't be ok to hit anybody, regardless of size, shape, or gender, but when people put themselves in the position to be hit, I don't have any sympathy for them. No sympathy for the guy in the original story since he shouldn't have opened his mouth in that fashion without expecting some kind of hostile reaction.

For t-girls specifically, I'd bet most people would say it is 'ok' to hit them, but to me it's less about what's hanging between their legs and more a case of trying not to hurt a person that may be physically weaker than you. I've known some genetic females that can physically hold their own against and hit harder than a lot guys, so I've never fully believed that a man should never hit a woman, much less a t-girl. It really all depends on the individual and the circumstance, but it's best to avoid hitting anybody if you can help it.