I love how everyone is optimistic, That's the way to go, What if John K died? Then what?
I dont know the guy but if he is human then he can get ill like anyone. If he were deceased then normally the estate would handle his affairs and clear this up. Not wishing any ill on anyone but regardless of the outcome of this now, if none of that were possible or outlined originally then it was an escrow setup badly.
The argument might be bitcoin is anonymous, it should have been set automatically to resolve like localbitcoin does