It doesn't have to be seen as bad for it to be undesirable. I'm straight, but I have plenty of gay friends and hold no ill-will towards any sexuality. I'm not trying to become gay though, so it isn't desired or, to use another word, it's undesirable.

I also don't really have any interest in buying a butt plug, at least for myself. Equating it as being gay makes it sound like it's something I shouldn't want, which there's no reason for that to be true. Even though I don't want it, there's no reason I shouldn't want it.