(I wrote this a while ago and had it in my drafts folder. I’ll publish it to keep at least a background level of controversy )

Sexual activity exists in perfection, as everything does.

“Becoming liberated does not necessitate losing one’s sensual activities. Sense activities continue even in the liberated stage. The difference is, however, that sense activities in liberation are accepted only in connection with Krishna consciousness, whereas sense activities in the conditioned stage are enacted for personal sense gratification.” Srimad Bhagavatam 3.15.31

“Heterosexuality” today (the cultural construction distinct from biological procreation) refers to a personal preference for a particular type of personal sense gratification. Devotees are not “heterosexuals”.

For service a man and woman form a stable socio-economic relationship and unite in order to produce offspring who are then brought up in a loving environment to become balanced, happy, spiritually conscious contributors to human society.

It is a service that involves sexual activity, not a sexual activity.

It’s a subtle but important distinction. Devotees do not oppose homosexuality out of personal preference for a different type of sense gratification as the people of this world do. We oppose sense gratification of any kind out of preference for divine service. That divine service is the natural order of the universe.

Whether it’s this bodily orifice or that one, same or different sex partner, if it’s not procreation in a spirit of service to the progeny and the Supreme Lord, all pervading and the creator of all living entities, then it’s not devotional service. It’s just trying to squeeze some kind of enjoyment out of your body and the body of another. The details are just that, details.