lol didn't mean to come off rude, I just skimmed it and missed it I guess - so the answer in this case is generally no you cannot relicense agpl 3.0 without being an original copyright holder and getting sign offs from all the other holders.

Also generally agpl 3.0 is considered a viral license, so accessing it over a network is considered a form of distribution (which is probably why they dont like it) but relicensing it is just a core "nope" type of thing.

(also dual licensing seems like you're relicensing effectively if the purchaser doesn't have to respect the gpl license, but not as clear to me)