In the 70's, the words Transsexual and ->-bleeped-<- were interchangeable and neither of them were accepted as a norm. The movie gained its poor reputation in the 70's because the character was so against the social norm, that people rebelled against it.
I think they are trying to be sensitive to the fact that "Transsexuals" (which, BTW, I dislike that term in general) tend to get borderline violent when they are called ->-bleeped-<-s.
Unfortunately, you can't change/remove ->-bleeped-<- in the song or it would simply not make sense. And, well, it wouldn't be Rocky Horror Picture Show.
The show has an openly gay character and they tend to be very sensitive to the GLBT world on the show, I doubt they changed it to degrade us. I wouldn't read too much into it.