I'd play it the same. There is the option of smooth calling on the flop and raising the turn but this player's so stupid might as well get in the raises when you can. This player's horrible; who knows what's gonna be shown to you on the river. I'd probably just call on the river out of utter confusion. This player does not raise with their sets so they might just be betting 2pr for value and getting scared when you raise. Then again, chances are that your overpair could very well be the best hand and you are missing an opportunity to win an extra bet. But still, they have shown some aggression on each street and the hand reeks of only one pair of kings (which should have been folded on either the flop or more likely the turn). The river bet is what confuses me--your opponent's logic may be "I'm going to call anyhow so I'd might as well bet with my Kings".

In summary:
I bet you're gonna see some goofy 2pair on the river.
You very well could have the best hand.
Your opponent is super passive; they might not reraise w/o the nuts.

I'd call the river and get ready to chuckle in disgust at the junk I get shown that wins the pot.