[skybrian]

Totally speculating, but "documented proof" seems to indicate that they would be satisfied by some sort of document? A screenshot would probably help? "Here is the screen where the user agreed to this" seems like it would be somewhat convincing. (If it's a screenshot then it will survive UI redesigns.)

Of course, from a security standpoint where the attacker is assumed to be totally untrustworthy, this is all nonsense since it would be trivial to fake. It does require a certain amount of trust that the company that will not stoop to faking documents.

I guess you could continue the charade by putting timestamped screenshots on a blockchain :-)