Such criteria are always arbitrary, since there is no universally agreed definition. How exactly do you decide whether the presence and participation of a person in a group is "pointless" or not? Ask five different people, and you'll get five different answers. Yes, you can point to extreme examples where almost all would agree, but the problem is that things are often not that clear.

The "protected" criterion is similarly arbitrary, except that the government gets to define that one. Even then, if you ask for a precise definition of when some category is considered protected in a given context, you must refer to a whole library of case law. (And you should also consult an expert lawyer who is knowledgeable about the unwritten norms and informal intricacies that usually apply.)

Unsurprisingly, humans being what they are, when they use such arbitrary criteria to answer problematic questions of law, ethics, etc., what they end up with are rationalizations for attitudes held for different reasons. Again, please note that I'm talking about something that practically everyone engages in, not some personal vice of yours.