Everyone should have access to public amenities. But a widespread homelessness problem ends up denying amenities to people who aren't homeless: when libraries regularly have people smoking meth or shooting up in the bathrooms, that makes it uncomfortable for most people to use. It's easy enough to say "they should just get over it, someone passed out on the bathroom floor is not really a threat to anyone," but that betrays a certain level of privilege that ignores the feelings of most people and the genuine lack of safety and cleanliness that homelessness introduces to those spaces.

In your hypothetical example, if you were inebriated, aggressive, and unhygienic, I'd strongly support you being removed from the subway circuit, because you'd similarly be denying access to it to others.