gay is more than just an attraction to cock. Gay is "I want to find a man and marry him and suck and fuck alot of cock along the way".
So doing a post op tranny is NOT GAY!! How could it be? It's certainly doing some strange, I'll grant you that. But just because the person doesn't have a female reproductive system does not make the actual sexual encounter "GAY".
Now pre op get's more complicated. Sorry BM. lol
I would say that if you do a pre op trannie you could be moving further away from the 100% straight end of the sexual continuum. Regardless of whether you actually touch her cock or not. Of course if you're sucking her off or letting her put it in your butt..........you would be even further down the continuum.