Oooh, I think I can explain this. Conservatism demands adherence to a an extremely homogeneous model of living. They’ve constructed this giant house of cards that relies on it. Accepting deviations from these norms calls into question a variety of foundational conservative beliefs. They effectively can’t question the status quo else everything falls apart.
The only option for them is to make LGBTQ people an unacceptable, dangerous other. Because if queer folk are normal people who just want to be allowed to exist, if there is no sweeping gay agenda, if maybe they read their holy book wrong … they’ve been behaving like assholes, for decades, for no good reason.
Their core identities would take an unacceptably heavy blow, so they have no choice but to double down. Well, that’s the case for the ones that care about internal consistency.
Some of them just want an excuse to be cruel to a group too small to fight back.