I don't think it's right or wrong (on the part of Airbnb, maybe wrong on the part of society as a whole -- there are federal laws for handicap/accessibility problems but not yet for self-identity not matching government issued identity)

The issue is that transgender people make up (I'm guessing and feel free to correct me if I'm wrong) < 5% of the general population. I would then assume that < 1% of the Airbnb population is transgender. That's a low enough number that it is more efficient for Airbnb to solve for those issues on a case by case basis rather than in code / process changes. Simple case of optimizing for the 90% instead of the 100% -- if that's offensive then I apologize but in my opinion it's justified in the near-term (maybe not in the long-term)