[Poshua]

This is not a case where "cards speak" is the key matter, because the hand is not at showdown. Villain had to call a bet to get to showdown. Regardless of what Villain's cards say, the question is whether his action of placing the cards in the center and declaring "I had you til the river" constituted a fold.

I think it's hard to interpret that action as other than a fold. Further, if it wasn't a fold, Villain and "Middle aged showdown muppet" have violated One Player to a Hand.

As such, I would award the pot to Hero. MASM gets a warning not to play others' hands. Villain presumably learns his lesson on his own.