Serious question. If this violates 50 year old Federal Law, how come this hasn't been done in the last 50 years? In other words, if 1964 allowed Gay Marriage, how come there weren't gay weddings in 1965? Why wait 50 years?
This has nothing to do with gay marriage.
I know but what I mean is...where did all of sudden all these hidden rules in Federal law come from? How come these weren't discussed in 1965 or 1975 or 1988 or 1999. How come it's all right now?
If the 14th amendment desegregated schools in 1868, why did it take 90 years?
Anti-discrimination laws are written as broad tools for a reason. The drafters of legislation like the Civil Rights Act know that they cannot foresee all of the silly forms of insidious discrimination that might arise in the future. For instance, no one was passing ridiculous bathroom laws until just now, so of course nobody tried applying Title VII to such laws before now.
The broader answer to your question of course is that we, as a society, have learned a lot over the decades and now realize that it was always wrong to treat LGBT people as harmful elements to be ostracized from society.