Is it really an "unreliable source", though? The owner of the site is acting maliciously with regards to this DDOS, of course, but that doesn't necessarily mean he's going to act maliciously about the contents of archive.today itself.
One could make the case that the owner of archive.today was already flagrantly flouting copyright law, and therefore a criminal, and therefore "unreliable" right from the get-go. Let's not leap to conclusions here.