He's not saying they have no right, he's saying he's sad they won't come to thanksgiving. Pretty simple. You can say its justified sure, but it doesnt change his perspective any.

It's not always simple. I have a close family with a NC child, and he's highly autistic and had been living at home until his mid-20s until the decision. It's not rooted in politics or abuse, and ultimately everyone hopes that sooner or later he figures himself out. But the temptation is very strong to reach out; and the temptation to say he's acting ridiculously is, like, not even overcome. We do think he's being ridiculous. And we sometimes say it. But with sympathy because of the circumstances. I think the author of the original post is probably a tithead, because he voted Trump, but I don't see him as doing that much more than what we do about this lad. Except for do it publically. And also he's the one who's been cut out because all of them have gone NC. So maybe not a similar circumstance at all, but probably still similar local emotional justification - i.e. I bet he feels similarly in many respects to how we feel.

Edit: I forgot to justify the relevancy. The point I was trying to gesture at with that was that moaning about it doesn't necessarily mean you think you're really owed. It's just moaning. But. As I was writing the comment I realised that actually the fact that he's doing it in a public forum under his own name is kinda different. And it goes from just moaning to, at minimum: chiding (since they could also see the message); public abuse (since their identities are - I assume - concludable from the message); and making himself the victim. So yeah actually I guess everything I said was probably all wrong, but I still rather like it as an exploration, even if it was of the wrong space, and I'm just gonna leave it up.