Hero is new to PLO but a 2-5 NL reg at the casino and villian knows this.

Hero stacked villian an orbit ago with AA, calling off on a dry flop and villian commented something like "**** Holdem players gii there with naked aces...". The spr was like 1 or less so it's whatever imo I'm not folding that flop.

OTTH

3 limps, hero(900)OTB limps 8776ss.(fold pre?) Villian in bb (1k)pots it, fold fold, shorty(100ish) calls hero calls.

Flop 10 7 2 rainbow. BB pots it, shorty all in for less, hero calls.

Turn J completes the rainbow. Villian check hero 175 villian call. River J villian leads 400 into 600ish... Hero?

Im calling as played because based on your description villain may be overbluffing here. He also may read you for the straight on the turn. Though if villain is generally solid he should not have many bluffs, maybe a weirdly played 89xx. But he should not be getting the right odds to call turn with most 2p, sets. All in player should also block some of the bigger boats.

Ugh such a grim spot, wouldn't bet the turn fwiw. Would hate to get raised off our equity there.
I think the problem here is that you repped straight OTT and now while his hand looks a lot like TT/77 OTF, he can rep boats on the river. He might have 89 and thinks he is trying to get you off a chop, he might have tens full, he might have like JT89 etc stuff also. Really really close, i think i'm folding as we'll definitely see villains hand.

raise pot on the flop.

My thought process on not raising here is that the only draw is 89, opponent is unlikely to have bottom set after raising from the BB, and he probably folds every single hand except TT. Not sure if he continues with the naked open ender here. Again I'm learning Omaha so I could just be wrong and raise pot is the correct play

This is a clear call versus described opponent. I would sometimes fold this versus nits who just only have it here especially with good tells. But even then I’d need to never ever see them spazz because the price is good and you beat some of his value on top of bluffs.

Call

he thinks you have a straight and he also thinks you're never folding a straight and it's free $400, so..

this is exactly the process which led me to fold...

villian had trip jacks for the bluff....

Generally you just shouldn't slowplay. In order for a slowplay to be the correct decision, a number of criteria must be met.

It must be a small pot. Here it is not. There were a number of limpers, then a raise and two calls pre, followed by a large bet on the flop and an all in call. The pot is already quite big.

Villian must be able to catch up to a worse hand. Here that is not really the case. What can villain improve to? Maybe two pair, but there are not really a lot of worse hands that villain can improve to. Mostly he improves to better hands, or big draws with a lot of equity like wraps. It's not like you have a flush and he can make a straight, or you have a boat and he can make a straight or a flush. You have three of a kind, a strong hand, but a vulnerable one, that can be easily be beaten by a higher three of a kind or a straight.

I agree villain is probably folding most of the time to our flop raise, but better for him to fold then to give him free chances to catch up to us. He's also probably not blasting any marginal hands like an overpair on the turn given that the main pot is now protected.

This couldn't be further from true. There are plenty of situations to slowplay in poker, regardless of game. Your decision should always be based on how to make the most money. Sometimes that involves putting in more action and sometimes that involves giving your opponent line.

A flawed way of thinking, especially in plo, is over protecting your hand. Sometimes it's best to give certain opponents line when your hand needs little protection.