why? he was a spaz playing super spazzy cos i had a crazy image too so i thought even by the river his range was super wide and included random hands like QJ with a diamond, Ax with a diamond, etc (ie no pair)
also, like many bad players in that vein, his bet sizes tended to be pretty terrible...
so i felt like he would bet if he had nothing, and if he had something, he would bet smaller than i would bet, which saves me chips too... and with the wide range i had him on, i didn't think that many hands were calling a river bet
in hindsight i might have had him pegged wrongly as he might have just been running super good and didn't bluff that much (though i did def see random bluffs from unplayable postflop hands multiple times), but from what id seen my opinion was that he was a random spaz playing any two cards poorly, who viewed me as a bluff-happy psycho
in that context folding a king there is unthinkable imo, it's bet (if you think getting him to call worse pairs is more important) or check-call (if letting him bluff/bet too small with stronger hands is)