Vatican II didn't cause it, the people that used Vatican II as a way to come into the spotlight did. With no Vatican II, you would have had homosexuals in seminaries and a rainbow banner where a Latin Mass is being said, I can guarantee it.
Yes, Vatican II's openness to the Modern World (Sigmund Freud, psychology, evolution, having seminarians watch Hollywood TV, and other errors) helped promote homosexuality that much more, and lowered the Church's defenses somewhat.
Let's put it this way: the book Goodbye, Good Men chronicles the Homosexual control of many seminaries, but it was all after Vatican II. I'm not aware of any "Lavender Mafia" dating before Vatican II.
HOWEVER...Anyone who thinks the Tridentine Mass -- the Mass of All Ages -- is some kind of Kryptonite to homosexuality (keeping it at bay) is nothing but a naive ignoramus.
The Tridentine Mass doesn't scare away homos at all. Quite the contrary! Many of them are quite fond of it. It's not a fault of the Tridentine Mass. It's because the Tridentine Mass is objectively beautiful even on a strictly WORLDLY level, and both GOOD and BAD people can appreciate worldly beauty.
The sodomy found within the Traditional movement proves this. Anyone who has more than a surface knowledge of the Trad movement knows that the Society of St. John was Trad, Bishop Schuckhardt was Trad, Fr. Timothy Svea of the Institute of Christ the King was Trad, etc.
A lot of homos like their "smells and bells" -- they are aesthetes. They like the finer things of life: culture, music, lace, wine, fine foods, etc.