I think the main distinction is whether you are attracted to specific people, and notice after the fact ("hey, I don't get attracted to females/black people/blondes") or if you decide "I won't date someone who is..." and then refuse to consider them based on that fact.
I do think that you can compare all of these things, because they're based on attraction. I think it is much more common to "discriminate" in who you're attracted to based on gender or sex than the rest, which is why the rest is usually considered fetishes. If you're unable to be attracted to someone who doesn't have piercings, you're not considered "normal", but if that's the way your attraction works, it's the way your attraction works. You don't get aroused? Can't be blamed for that.
If, however, you say "people who don't have any piercings are stupid and boring and I refuse to associate with them", you're passing a judgement and you are bigoted and discriminating (YOU are discriminating, rather than your libido doing it).
It might be hard to draw the line (do I not get aroused by X because of some internalised judgement I am not aware of, or is it just part of my "orientation"?) but I still think that if you're not ever attracted to someone who is X, that doesn't mean you are necessarily bigotted against X.
Now, it seems weird for things like that to work on "changeable" attributes. For instance, if you can only be attracted to long hair, but neglect to tell the woman you are dating, and she has a hair cut, are you suddenly unable to be attracted to her? Do you have to wait for 2 years for it to grow back before you'll consider anything with her?
With hair colour, would dyeing it work, or is it a hormonal thing, so that you can tell anyways?
But ultimately, I think as long as you know what you want, you're golden.
Now, if I think back about everyone I've been attracted to, not a lot of them are part of minorities... but I also don't seem to hang out with a lot of people who are, for some reason, so I don't think I'm less attracted to them, they're just a smaller pool to begin with. On the other hand, I know I'm not attracted to females at all. And when I was younger, I was not attracted to men younger than their late 20s, but this has changed.
As long as you follow your arousal and preferences rather than try to dictate them, I think you're good. The bigoted person is the one who still won't date Xs when they start being attracted to them.