I found a longpost that sort of covers the same ground. Edit: tagging u/YesMovement because I guess this tweet references a Canadian meme.
https://xcancel.com/OthmanOnX/status/1881906094605500749
With these in consideration, my evolutionary psychologist tulpa has a thought.
This is basically gatekeeping your community (family, tribe, country) in life. An outsider visits and finds something they don't like about this tribe, probably based on the values of their community. In a primal time, this friction might carry the threat of violence. The tribe might just kill the outsider or, if the outsider represents a stronger group, the outsider might hold sway. Of course, we're mostly a "dignified" world now, so some of this is turned to social pressure and these days, everyone knows that we must accept each other despite everything (unless they're bad-ist).

Moral justification or acquiescence imply you need to become agreeable to the outsider, that they have some authority over you. Offense or derision challenge this authority/expectation of fitting their values.
It's very much like the comic where outsiders insist some small group/box welcome more people, and then eventually the original members ultimately get filtered out.
TL;DR: You don't shoo away people that have no intention of fitting in, you lose your community.

I found a longpost that sort of covers the same ground. https://xcancel.com/OthmanOnX/status/1881906094605500749
With these in consideration, my evolutionary psychologist tulpa has a thought.
This is basically gatekeeping your community (family, tribe, country) in life. An outsider visits and finds something they don't like about this tribe, probably based on the values of their community. In a primal time, this friction might carry the threat of violence. The tribe might just kill the outsider or, if the outsider represents a stronger group, the outsider might hold sway. Of course, we're mostly a "dignified" world now, so some of this is turned to social pressure and these days, everyone knows that we must accept each other despite everything (unless they're bad-ist).

Moral justification or acquiescence imply you need to become agreeable to the outsider, that they have some authority over you. Offense or derision challenge this authority/expectation of fitting their values.
It's very much like the comic where outsiders insist some small group/box welcome more people, and then eventually the original members ultimately get filtered out.
TL;DR: You don't shoo away people that have no intention of fitting in, you lose your community.