your ruling?

[Mackie]

At the river other player bets, I call, he mucks. As dealer begins to push me the pot I muck my cards face down. Other player says "I get to see those". I look at the dealer who looks as dumbfounded as I am. He says "If you call the river you have to show" which I know is wrong but don't say anything. I can tell right away I will either need to show or call the floor to get a ruling, which I think would go in my favor. The other player was a hefty contributor so I make the quick decision to show and get it over with. Noone else at the table asked to see my hand, just him.

Would the floor have ruled in my favor? Would you have just shown as I did or asked for a ruling? Perhaps just fling your cards into the muck face down?