If it's obvious that someone is on tilt - say a tight player who just suffered a bat beat - what's the best way to talk advantage of this, assuming that chat isn't on? I'd assume that a tight player would open their range quite a bit and call or raise in questionable spots, along with being stubborn on taking draws too far.

Do we push more high pairs pre and post flop - something like three and four betting KK97 or QQ67?? Check raise the flop more often?

hehe.. I lost a lot of money trying to take advantage of players on tilt in PLO. Its tough. Especially a good, TAG player on tilt. I tried opening my own range up to abysmal results. I would target them and go out of my way to play extra pots with them figuring they would steam off some money. And sometimes it would work, but it would take me out of my game and more often than not I would run into another player playing sniper and get stacked. I have since learned to just be patient and play more normal game. Perhaps calling down in position and c/calling oop a bit wider if you are HU with the tilter. They may be more apt to 3 barrel, so you may have to call with non-nut straights and flushes and two pairs.
But don't start calling down with overpairs in spots you would not normally. A TAG on tilt is more likely to overplay AAxx and you are just paying that off. It cost me thousands to learn this.

There is a ton of money to be made in PLO just by being the most emotionally stable person at the table.

dont over adjust by widening your preflop GII-range. equities run too close in plo to get massive ev from gii with kings or queens... rather milk his tilt ev postflop
you can widen the range of doublepaired hands for example, because if u hit a set you have giga implieds vs a tilt ape

In my view you should not widen your overall range at all. In fact, to exploit them you should TIGHTEN your overall range but be more liberal with 3-betting and check-raising to take advantage of their tendency to over-bet or make crying calls when they are at a range disadvantage. Don't 3-bet trash like QQ67.

+1 all of this

Not looking to widen my range but I am definitely going to isolate exploitatively. In spots where I would typically just call IP,

I would steer away from 3b hands like QQ67. These are even questionable calls IP unless it is DS. I would prefer to 3b with A876ds or AJJTds because we block AAxx and are less likely to be 4b. If we face a 4b with QQ67, we are in a world of hurt but I will take A876ds and AJJTds to 4b land IP all day.

QQ67 isn't questionable. It is a fold.