What "sort of behavior"?
Clear and fair warning? And expectation of cooperation with a large existing community? A public statement of intent regarding counts from the ruling duke?
Sure, immediately ostracizing any random that happens to set foot in your land would be unfair, and against the "spirit of play".
But that's not what it happening here, and for someone who seems to be frustrated with people "putting words in their mouth" or being presented with strawman arguments, you seem oddly inclined to do the same.
If people were claiming some type of "you are not in my community, therefore we will immediately attack you" approach, I might see where you are coming from. However, that's not happening either. Most of these posts are from the angle of "we have a community, you are welcome, just reach out".
To maintain the poker reference - these communities (especially the large ones that have filled their domains at the count level), have already chosen the hand they want to play with.
It may not be the best hand, but it is the hand they are betting on. "Forcing" them to take another card, under the guise of "you might get a better hand" is just as "bad" (IMO), as refusing to take another card.
Play how you want. This isn't "harassment", it's simply a desired style of play.