What remains is not allowing homosexual couples the same treatment as heterosexual couples, because heterosexual couples are "special" for religious and traditionalist reasons. This is very strong identity politics, but from conservative side and very much contrary to the spirit of "live and let live". It strikes me how many conservatives do not realize that they very much support identity politics and then go raging against it the next moment.
Treating people equally should be the default and is the result of not caring about identity in the first place. There are some good arguments that can be made for identity politics after that, but the case against equal treatment should have to be a really strong one. Traditions and religious feelings do not suffice for that in my opinions.
Even when the absolute numbers of homosexual marriages is very small that doesn't justify not caring about unequal treatment. Imagine if we would tax all identical twins 5% more than everybody else. This nonsensical unequal treatment would clearly be unacceptable injustice while the percentage of people that are affected is still very small.
On top of that there are social explanations why homosexual people would be less likely to marry. Marriage has long been a religious and traditionalist institution and has been used to discriminate against them. It can be hard to identify with such an institution and I know queer people who would not like get married because of that. If marriage had been available to everybody since as long as they can remember considering marriage would perhaps come more natural.