The straight community responded to this by stopping and winding down the free-love sexual revolution.

When did that happen? Only some fanatics created the Moral Majority, but the Actual Majority just ignored them.

the disease has never broken into the straight community

What? What planet are you looking at?

they would describe having homosexual sex as a sin

That's a different type of argument. The notion of sin rests on assumptions that are alien to facts. An objective description of a self-destructive behavior will need more solid arguments.

a lot of boo lights and emotional language [...] social pressure applied to people doing destructive (or self-destructive) things is a great way to encourage them to stop.

Let me put it in more neutral terms: being gay is not destructive or self-destructive at all. As simple as that. If society wants to minimize harm, it must focus on the specific factors that cause harm. For a concrete example: nobody denies that anal tissues are more delicate and facilitate the transmission of infections. But from there it's a very long jump to claiming that men loving men is lethal.