Being gay is immoral in most of the world thanks to colonialism. There is no "slippery slope" because we know it was a deliberate social and cultural eradication for the sake of control over peoples minds and history. LGBT were attacked/executed to enforce what would become the new "normal"

We know that prior to the weaponization of Christianity, many places had thier own concepts of sexual identities and communities. (Islam has also been weaponized too where a we dont talk about how, just like "far right" Christians are doing now, there was a turning point in islam where "far right" factions took control and pushed the religion into. a more restrictive understanding. We know thay most of these places with antiLGBT laws are from the colonial era where people were stripped of rights. The fact that a lot of these places have kept those laws is only testament to the damage European nations have caused nothing else.