But what do we need this most carefully thought out cleverly eloquent contract for in the first place?

 1 - does the gentleman hacker say to the real cracker 'hey man send all the btc back to big ole vern, once he receives it all, he will then give us some back coz we got a contract' ?

 2 - or does the gentleman hacker himself move all the btc back to big ole vern and once he receives it because of this lovely contract he expects paul to send him back his bounty ?

And mind you if something should go wrong, we can decrypt his pgp and learn who he is. That is what ? In case big ole vern does not honor the contract?

Hey how about this.

We make an even nicer more cleverly thought out contract where big ole vern agrees in writing that you keep your bounty and just send the remainder to him. Or if you have this believable way to recover the btc, instruct the real cracker to hold back the agreed upon bounty just send the balance to the specified address.

Because we are all in agreement that we are entitled to retain the agreed upon sum. Stated right there in the contract