If someones bi-curious for a cock in isolation but finds the broad shouldered, lantern jawed, hands like shovels bloke attached to it either about as sexy as a plank of wood or actually sexually repulsive then that doesn't strike me as falling into a clear cut category of being gay as most people take it to mean. 'Limited bi-curious' maybe a better term
yeah, ok, maybe if you want to be totally rigidly semantically strict then:
A TS is genetically male despite the predominantly feminine appearance (of the best ones). XY chromosomes or whatever.
To be gay is to have sex with a man.
To fuck a TS is gay.
But the subtleties and variations in human perceptions and sexual responses aren't limited to that and make shagging a good looking TS qualitatvely different from shagging some geezer called Derrick.
I reckon it depends on whether this is an argument about what the limited range of words available to use on the subject mean by their strict definition or what people actually feel like.