> Last I checked, they had archive.is blacklisted; the people with power there had (as far as I can tell) come to the conclusion that people using that site to prove that websites had stated X on date Y were the bad guys.

Or they're worried about the paywall by-passing functionality (which is probably what a good portion of people use it for) and copyright claims against archive.today potentially having it taken down and thus breaking a lot of links.