Correct Ruling? Hand Tabled Across Betting Line

Late night 2/5 game, our storyÂ’s protagonist is some combination of drunk, doesnÂ’t speak English well, possibly some sort of mental abnormality. When he speaks, heÂ’s mumbling quietly, he needed bomb pots explained to him, but easily knew how to post when coming back from the bathroom. Just sort of erratic like sometimes he was present sometimes he wasnÂ’t. His play also erratic, fairly active , showed down a few junky hands, weird sizings.

Protagonist gets to the river heads up with ~$800 in the pot, AQJXX with a diamond flush possible. Protagonist bets $400, villain jams for $500 total, dealer announces all in and puts out the all in button. Protagonist mutters something unintelligible , then tables KT no flush across the betting line, not near the muck. Villain is on other side of the table , says something like “you don’t got a flush I got you beat.” Does not table hand.

Dealer waits maybe 3 seconds then mucks protagonists hand, begins to push pot towards villain, someone points out protagonist has a straight, pause, table sort of erupts into chatter, villain asks dealer to call the floor.

Floor rules that tabling the hand with a forward motion across the line when player hasnÂ’t called the raise is a fold, specifically saying the dealer is trained to muck the hand immediately in this situation.

Correct ruling? Just kind of a crazy situation, where the guy obviously wasnÂ’t folding, some speculated he thought the other players all in was less than his bet. Worst part is he didnÂ’t say a single word in his own defense