You just answered your own question. The logical defense is that it's accurate, as opposed to one that's not.
No listen. Jesus. You are not being logical. It doesn't matter if Tenshinhan is the original CORRECT name, you still have not, and probably never will, provide reasoning why you are essentially enforcing people to use a specific name instead of another. That is something that is WRONG. You can say it's insignificant but Tenshinhan's TRUE name is debatedly insignificant too.
It IS wrong to do what you're doing. It is elitist, immature, and ultimately pathetic. If I want to call Tenshinhan "Pink Supervisor", it's wrong, it might be annoying, but why should I be prevented from doing so?
Yes it IS a big deal, because it's not just down to how easy it is for me to say Tien, it's a disturbing and disappointing insight into the kind of people that almost always end up owning and running forums. Does that make me an immature rebel? I don't care. I still have a point, and people who throw out anti-authority stereotypes only do so because they know their authority is questionable at best.
You don't understand logic, at all. Just because one name is the more used or the original name doesn't mean you should force people to use it. That is NON SEQUITOR. It does not follow from one point to another. You still have not defined why people should be forced into this crap.
Logic is not an opinion - you are objectively in the wrong here. Until you grasp the point that even if a name IS correct you shouldn't. This is an issue of logic and respect. You keep up with this ulterior motive crap because you can't deal with the point head on. I just genuinely can't stand illogical, unfair decisions.
Tenshinhan being the correct name does NOT mean you should in any way force others to. The fact that there is a way around it is secondary, if you banned people over it there would be a lot more people who wouldn't take this shit. There is no logic connecting point A and B.
I'm really loosing patience here. You're not prepared to entertain the opposing view at all, just continue with the patronising It's Great To Hear Other People's Opinions

when you couldn't give a toss and don't even begin to respect those opinions in the slightest.
I'm probably coming off as a jerk now but I'm so frustrated. At the end of the day,
you're not listening.