1. Regarding names, call people by their names. Unless you have some reason to argue that a person cannot change their name, which would be absurd, then call people by what they call themselves.
Exactly how far do we want to take this kind of principle? Suppose someone says their name is 'The Lord God Almighty', or demands to be addressed as 'My Lord Emperor of the World'? Because you know damn well that there are going to be people who are going to make exactly those kinds of demands just to see how far they can take it and how many people they can manage to piss off by making outrageous demands to be called by a particular name or title. There are a shockingly large number of people who post at 4Chan.
We take it where it is reasonable. There are certain things that, by convention, we simply understand are not names. There are certain things that clearly are. There are gray areas. And while gray areas really are gray and there may be some tough calls on this or that case, I'm reminded of something PED said years ago -- just because I may not know whether or not a virus is alive doesn't mean that I don't know that a horse is and a rock isn't. "My Lord Emperor of the World" isn't a name. If someone thinks it is, have them go to court and have their name so legally changed. It won't happen. If John wants his name changed to Jane, there probably aren't any courts in the country that would forbid it. In short, let's not make a few possibly difficult cases in applying common sense allow us to throw common sense out the window entirely.
Also, to take into account Jack's comment just above, there is also the matter of naming conventions themselves. While you can find stories of people who flout the conventions (some pull it off, legally; other's get shot down by the courts), the fact that such stories are so easily identifiable are the exceptions that prove the rule. But those conventions are relative to the culture, and different cultures have different conventions. Who, today, would name their kid, "Who is like God?" Well my mother gave me that as a middle name (Michael, as I'm sure you already know). So, by convention, "Michael" is a perfectly legitimate name that in its original language means "Who is like God?" But even in Hebrew there were and are conventions of what constitutes a name and what doesn't. I bet almost nobody would be able to list those conventional rules in a meaningful way, but everyone recognizes, within the contexts of their own cultures, what constitute real names and what don't vs those that are really, really weird and are just pushing the boundaries. Different cultures, different conventions. And as it applies to this conversation, again, some dude wants to legally change his name to Jane, then that's what you call him. That's his name whether you like it or not. He wants to change his name to "God Almighty Who Must Be Worshiped Upon The Pain Of Death And Eternal Torment You Know This Is Funny That I Can Make My Name Whatever I Want JaJaJaJaJaJa Hey Look Funny Spanish Reference In My English Name I Am Such A Troll" -- well, as my brother says, he can go kick rocks. That's not a name. You know it. I know it. He knows it. And that's the end of it. He can just be John, or if he wants a weird name, Apple or Blanket are just fine.