Given your explanation and interpretation, I think we all need some time to better consider the aspects of this matter, at the moment, I now understand a showdown no-one can 'fold' so to speak, so all cards are live unless they land in the muck.
I recently ran a tourney in Aberdeen where at showdown ALL cards must be tabled, which went well, but it is a bit archaic and dictatorial.
I prefer to allow players to muck, if they pass their hand freely then they have surrendered their claim, if they pass as a result of mis-information then the floor can retrieve the hand as per RROP.
With regard to verbal statements I think there is going to be few statements that can be made, cards speak for themselves, as per RROP verbal declarations are not binding but misleading other players may result in a penalty.
Stuart