A lot of laws are based on morality. I appreciate morality. And for what reasons would you ban homosexual marriage that aren’t related to morality?
“Based on” is a whole world away from “Because of”.
As to the rest. Homosexuality is purely about a specific type of sex - Male/male Female/Female. What other laws/rules/regulations or RIGHTS are determined by a sex act? BDSM? Beastiality? Leather/rubber fethisism?
None. That’s for starters. I can freepmail you an entire chapter of a book I’m writing laying this particular argument out fully if you like.