Inform him that you are keeping his snake as payment for the one you lost. Just call it even with him and walk away with a lesson learned.

If the guy really is selling his collection, then outting him on the BOI will just cause drama for drama's sake and won't really affect him in the long run.

On the other hand, since certain people who frequent the BOI live for drama, go ahead and post the story...might spice up their Monday over there...