It is literally their community. They host it. They moderate it.
"Lemmy" is not a community, it is a loose federation of instances that can choose not to federate with other instances.
Your outrage seems based on "HOW DARE THEY BLOCK US FROM OUR COMMUNITY", but it was never yours. You were merely allowed to use it
They already said they won't remove old
You know, like they said API pricing would be reasonable.
Count your days