Let's keep going with this analogy. A city has some set of just laws - assault, for example: you can't just run up to strangers and scream at them and make them feel unsafe.
A meetup is a social event, and as such it has social rules, which are the equivalent of laws here. Making people feel unsafe and being an asshole is breaking those social rules.
A city can fine people or put them in jail; a meetup can forbid people from attending.
One key problem with this analogy is that everyone has to live somewhere, even the homeless. But not everyone needs to go to a special interest meetup. The organizers of the meetup didn't owe more to this one asshole than they did to the group, yet they made the entire group pay the cost of interacting with him.
A meetup is a social event, and as such it has social rules, which are the equivalent of laws here. Making people feel unsafe and being an asshole is breaking those social rules.
A city can fine people or put them in jail; a meetup can forbid people from attending.
One key problem with this analogy is that everyone has to live somewhere, even the homeless. But not everyone needs to go to a special interest meetup. The organizers of the meetup didn't owe more to this one asshole than they did to the group, yet they made the entire group pay the cost of interacting with him.