I see no reason why not. People put plenty of things, preferences, lifestyle choices that are completely irrelevant to gaming into their screen name. The whole "it has nothing to do with gaming" bit is a pretty worthless argument, because a screen name has nothing to do with gaming, but everything to do with identity. If this is how a certain person wishes to be viewed and acknowledged as, then so be it, we all get the same treatment in allowing other aspects of our personality to shine through.
However, the problem that arises from this is moderation of screen names. It's no secret that every gaming community on the planet has rules, and in those rules come naming policies. Those policies are there to keep people from being offended by the obvious offenders, such as names centered around hate towards sexual preference. Where the lines start turning grey are when you allow the use of such words in a screen name, and have to police which ones were meant to be offensive, and which ones were meant to just simply state the fact. With how crafty people are, and how inconsistent the people policing the names can be, it can turn pretty tricky and in the end cause more headache than it's really worth.
Because the internet is such a rampantly immature place, I wouldn't be totally surprised if most companies maintain their stance on their naming policies for quite some time. The more publicity it gets, the more likely they are to make a change, but it's going to take some serious reconsideration for how they address naming issues before it can really take effect.
