I stand corrected. You are correct, they did have transgender rules in the 1960s.  In looking up the information I also found that there were transgender people serving in the civil war. My guess is that even though surgeries became available in the 50s, it was not very common until the 80s.  Mostly in the service you'd be talking about women that dressed and lived as men. Just considering the realities of society.  

Regardless, any civil rights act could be treated the same way by that standard.  If we did it for 50 years it should be more right than something we changed recently.  That is faulty logic.