Death to NATO refers to the dissolution of NATO itself, it is not a call to actually kill anyone.
In reference to landlords, I mean personally I'm with you on that, but the alternative is reeducation, which the right will ultimately view and espouse as prison. You cannot be anticapitalist and pro-landlord, the ideas oppose each other at their cores.
It's from a lemmygrad user and posted in lemmygrad, so I think it's safe to say it's a joke. They're riffing on the other instances wanting to defederate from us, when we all know that's not gonna happen here