I don't like fat chicks, that doesn't mean it needs a different loveuality.
But being fat isn't a gender. That, and biloveuality, outside of it's common "I forget everybody" meaning as you've described, fits for those who are simply turned off by herms.
There are, at a biological level, three genders: those who have both a peepee and a vagoo.
There are also guys with vaginas, girls with richards, and people with nothing. Really, anything can go on with a person's body given the right conditions, lol.