Aaaand this is exactly the reason why we are expected to take all this bullshit seriously. People who are just liberal enough to either have no preference or concede to "it's not hurting anyone" are slowly giving more and more social territory over to the crazies.
Sure, if someone wants to be a horse, YOU can call them a horse if you want to. But it's only a matter of time until not calling a them horse can result in legal action against the rest of us who refuse to comply with some stupid shit like that. And that's not a slippery slope fallacy because it is literally already happening. The Equality Act will hardcode gender identity as a federal protected class for example. "Horsegender" is a gender identity. Do trans people deserve equal treatment by society and equal hiring opportunities? Absolutely. Does a fucking weirdo who thinks he is part horse deserve equal treatment in any way? Absolutely not and it's okay for us as a society to draw a line somewhere. But that "line" is entirely absent in any LGBT legislation and it is 100% on purpose.