The reason the student protests of the 1960s didn't lead to political correctness was precisely that — they were student movements. They didn't have any real power.
I don't know what Graham thinks 'political correctness' would have looked like in the 1960s – most Americans still thought women's lib was a joke, many Americans were fighting to preserve segregation, and nobody had heard of such a thing as a gay rights movement.I don't think its totally unknown in the past although I suppose you might say it was often done with implausible deniability. As people pointed out there's a difference between being out and being openly out.
One funny example was https://en.wikipedia.org/wiki/Vladimir_Zhirinovsky (Putin's fascist clown who played the extremist to make Putin seem more reasonable, although it was probably close to his real views). Surprisingly the antisemitic Russian ultra nationalist had a Jewish father(who divorced his mother and moved to Israel when he was an infant) which he used to sort of deny it in a ridiculous manner saying his mother was Russian and his father was a lawyer