The Marvel Ultimate Universe was created in order for them to tell stories that can't tell in the main universe- to reinvent some things with greater liberty. There seems to be this new wave of multi-cultural super heroes that they are pushing. DC will have more "color" in its reboot in September. They will have the Asian Ryan Choi be the Atom, for example, instead of Ray Parker.
As far as him being gay, I think (like ethnicity) comics have always done a good job of being places where kids find comfort and escape and part of that is seeing people like themselves. I remember the power of the New Teen Titans in the 80s, especially their stories about runaways, teen prostitution, and teen drug abuse.
There are several out and proud gay X-men running around currently. Off the top of my head I can think of Northstar (revealed a few years ago that he had a crush in IceMan) and is married to an African American, Karma who has been shown in bed with other women, Rictor, Shatterstar, Destiny, Mystique (always was implied that she and Destiny were lovers --technically bisexual), Daken (Wolverine's son, also bisexual), Anole, and more. Plus, the X-Men moved to San Fran, so it only made sense.
Complication makes it easy to explain failure.