I do actually think there is a responsible way to write queer villains, and basically all it boils down to is “don’t make their queerness the villainous thing about them.”

They can be greedy, or violent or vicious or whatever, but these traits should be the thing that is terrifying about them, not their sexuality, gender, or gender expression. And the way they are presented, framed and reacted to by other characters should reflect that.

( also, imo if you have a queer villain, you should probably have some queer heroes too. :\ )