other than that they are all your assumptions again of what they would have asked DPC for (complete with evil plan as if DPC was the last of the dummies), but mostly it is not true
but why do you think DPC wrote to them 4 years ago? out of courtesy between artists?
DPC was aware that they might not be favorable, and sought reassurance, then having received no response proceeded anyway
the conditions haven't changed (DPC doesn't say, where did you find that out?), only now the authors have responded to him and told him that they don't agree with his use of it
that a song is free means that you don't pay for it not that anyone can use it, the authors always have the final say.
then it's believable that by paying they would change their minds, money suits everyone, but it's just castles of cards, in my opinion there's no basis at all, no AVN pays, assuming DPC paid it would be pocket change that wouldn't make a difference either way
let's say even 5% of what he has earned so far (which is a huge unlikely share) we would be talking about 15,000€, you don't even pay the lawyer