One of my local casinos does a weekly 4/8 full kill h.o game. I'm no Omaha expert but I like the game and play occasionally.
It's a typical O8 game with 4+ to the flop.

Kill is on. We are on the button and have Kh Ks 2s 3d 2 limp. We call. Sb folds and bb completes killer checks so 5 to the flop of Qs 9h 4s. BB checks killer bets. 1 call and 1 fold to us and I call. Turn is the 7d. Killer bets 16 and other player calls. We call praying for the ole A for the legendary nut nut. Instead it's another 4. They both check quickly and i pause for 10-15 seconds to think if there is a reason to bet for value. No straight possible. No flush. No low. The killer would surely fire if they are betting twice and the 4 fills them up. The caller can't check a boat right? Basically comes down to if someone has an AAxx hand that beats me I'm thinking. Would a $16 bet get AA to fold ever?

Let me know if you think there is value to betting here in a typical O8 game. Also the killer is a very active player.

Yes, but given your (likely very passive) image its super thin

Really you should by raising pre, as played would also strongly consider raising flop

You're asking two different questions about the same scenario: (1) Is there a reason to bet for thin value? (2) Is there a reason to bet as a bluff (hoping, for example, to get a better hand like AA to fold)?

In a typical $4/$8 game, my answer to both questions is no.

This is a prime bluffing board in that all the draws have missed. So if you had something like A256—and if you were playing that hand aggressively all along—you might want to attempt a bluff here, as you have no showdown value. Basically, you're hoping no one has a 4 and no one has AA—those two hands are going to call for sure. And although I agree it's unlikely that either of your opponents has a full house here, you might be surprised how many players would check their A4 in this spot in a passive low-stakes game.

However, with KK, you have showdown value. You lose to AA and any 4, but you beat hands like AQ, KQ, QJ, or Q9. The problem is you don't know which of those hands your opponents might have, the ones that beat you or the ones you beat. For that reason, I would just check it back and hope for the best.

Now let's suppose you want to bet for thin value. What worse hands do you think will call you? Probably not KQ, QJ, JJ, or worse pocket pairs. Even Q9—top two pair on the flop—knows he just got counterfeited and now loses to any boat, any 4, AA, or KK. Maybe AQ would call you here, or Q9 if he suspects all you have is AQ (or that you're bluffing). But unless you've established a propensity for bluffing in this game, most of the hands you beat are going to fold—and most of the hands that call you are going to have you beat. So again, absent any strong reads on your opponents' holdings or tendencies, I would just check it back in this spot (and hope for the A next time, of course).

I think this is a check along situation, agamblerthen has it nailed down. You describe the game as a loose weak game. Yes, you prob have the best hand now, but betting the river only puts us in a bad situation if raised or called.