At any rate, I'd say that the burden of proof is on you to show that homosexuality is harmful in anyway. I can certainly show how oppressing homosexuality is harmful. The history of people being assaulted, tortured, and executed for homosexuality is know and I assume I don't have to go demonstrating its occurrence to you. I think we'd generally agree that those things happening to people is bad. Also, there are cases like that of Alan Turing and the countless others who have been subjected to vast psychological harm merely for being gay.
And in case such specifics about homosexuality seem like a derail from the OP, I think these examples illustrate how absurd it is to include non-acceptance under the umbrella of acceptance. How can I be accepting of certain people and also be accepting of those would treat those people the way Dr. Turing was treated? Now that would be hypocrisy, or actually outright self-contradiction.