You'd have to find a law that prohibits a non-host to ask a person to leave private property.
If the owner of the private property allows a guest to do anything, what can you do? Asking you to leave because you are not a dub is not illegal. If they didn't like you because you are black or homosexual, or Jewish, or a Jehovah's Witness, or any other division of the human race, so be it. It is not illegal. It is why private clubs are still allowed to exist and exclude members. (ie, the KKK is not forced to allow whites into their little private group). Unless the property owner objects and shows that the non-host was exerting undue coercion, nothing to be done.
We may not like it and it certainly seems reprehensible for someone (JWs) who claims to be "Christian" to show such utter lack of love, but there is nothing you can do about it. It is not illegal... such people are just being an ass. And if being an ass were illegal, there would not be enough people left walking free to be the guards in the prisons for all the locked up asses in the world.
Now if the non-host allowed someone to do something illegal, such as allowing underage drinking, and the private property owner allowed it, then of course law enforcement would be interested...and both the non host and the private property owner would be held legally, civilly, and criminally liable for allowing it. Whole different story.
dunno...just thinking out loud...
Snakes ()