Well if the guy in a dress starts demanding to use the female toilets, do the females in the office have any right to be uncomfortable? Or if he keeps using the male toilets, do the guys have a right to be a bit confused when he's doing his make up opposite the urinal? Should you be disciplined if you are confused with the situation?

Its not that people might overtly or deliberately say something offensive, but the lack of understanding around how to treat this issue may well lead to others being treated unfairly. Theres an expectation that everyone shouldn't even consider being shocked/surprised. Do you seriously think the vast majority of people would have no reaction whatsoever if a tranny turned up the their place of work who used to be called Bob and now said he was Brenda? Its an OBVIOUS change which people will naturally react to, its not comparable to racism -already though, and you're proving it, I can just see people being accused of that level of hatred if they fail to understand/accept things...