He isn't. Literally. They just wrote two gay guys into his story to be possessed by him. The lore in no way, shape, or form mentions his sexuality or anything about him other than "Sadistic Darkin who got sealed in a bow, then possessed some hunters and is out for vengeance."
Probably because until this point Varus was the human. Everyone who liked the old lore still thinks of Varus as the human.
Now that the humans are gay, to them Varus is gay.
It's not about gay people, it's about the fact that who Varus was is completely gone for pretty much no reason
Varus cannot be gay because the two males are yes, indeed gay but since being gay is a negative thing therefore when you multiply the two negatives together you get the positive outcome of Varus therefore making him straight! I state my case. CASO CERADO*[slayer-pantheon-thumbs]* 
