To me it feels like you are arguing that the guiding principle for whether an action is "antisocial" is whether you are free riding or imposing externalities: getting a benefit at other people's expense.

Which is a fine moral principle, and does easily distinguish between all your "antisocial" examples and my "housing choice" example (assuming correct prices).

But it doesn't seem to require the "what if everyone did it?" principle. So I'm wondering if that principle brings any additional value, or indeed if it is a real moral principle at all. Hence my question.