I don't think they're lashing out in self-defense. This is a harmless way for them to get attention, which is what they're desparate for because the FBI is after them at the behest of Bezos and other billionaires who control the paywalled media and don't like archive.today's role in making them accessible. The only thing that could possibly save them (though it almost certainly won't), is gathering as many eyeballs as possible from the people who like the service. HN having a super high concentration of those. Almost every paywalled post here has an archive.today link in the comments.
That's also why they posted about it on HN, explicitly under that name. To get HN eyeballs.
It's intentionally harmless because, as you confirmed, it's not costing you any money or resources.