Yep, they're trolling on purpose; but also fully within the rules. There's nothing wrong with what they're doing, per se, but they are using the mechanics of the tree to be douchenozzles. ¯\_(ツ)_/¯
I worry that our conversation on here will have the same effect as the complaints threads on Board 7, and encourage the 6 NPers to continue for longer than they would have otherwise.
Best thing you can do is feel some sympathy for them, because someone who finds pleasure it behaving spitefully towards others can't have much joy in their lives.