As far as I understand the person behind archive.today might face jail time if they are found out. You shouldn't be surprised that people lash out when you threaten their life.

I don't think the DDOSing is a very good method for fighting back but I can't blame anyone for trying to survive. They are definitely the victim here.

If that blog really doxxed them out of idle curiosity they are an absolute piece of shit. Though I think this is more of a targeted campaign.