He 3-bets 100% of my opens. His C-bet is always pot. This is always how I run vs. Aggro-Tard player type.

I seriously can't beat the retards to 3-Bet + C-Bet 100%. They just keep doing it. I just keep missing. Finally I get some piece of something and they have a bigger piece. They catch on the turn or river when I'm calling them down or when I raise them and they stack off with a Jack high flush draw and hit it for a 4-buyin pot. Sigh.... 700 Below EV now this month. And quite frankly that's not calculated correctly because it's more like 2 or 3k when counting the number of times I"ve been sucked out on the turn or river with 80% of stacks in. Sigh

Very important read: bets smaller when weak and pots when strong (based on this and other hands you posted).

If he 3best a ton, then stard 4betting a lot - any QQ+, any ABB (ace,broadway,broadway), any AK not rainbow, any A+ds (except total trash), any 99+ with connected sidecards (or side cards T+)
any ds rundowns.

Also tighten up to 80% from the button.
Try minraising some and 3x other hands, if he stops 3betting 3x opens then switch your range and minraise stronger hands and 3x weaker (or just stop minraising and keep 3x)
You could try to minraise entire range, but i think 3x entire range is better vs 100% 3bettor.

I tighten up like crazy on the button but even then I'm still getting run over. Most of the time we both flop nothing and they instantly pot.

4-betting to take back initiative makes sense but the problem is at PLO50 that creates a $27 pot. At that point we're just gambling to see who flops better. Rarely are we better than 60/40 PF so what does this do other than create massive gambles and hope to run good?

I feel like it's better to flat the 3-bet and figure out an intelligent range to raise the c-bet with that takes into account both board texture and my own hand strength. Honestly that range could be as wide as 2nd pair or better with 4+ nut outs. Its hard to say but I feel like the only way to beat these players is to re-aggro them into the ground with the appropriate range.

You seem to be 'scared money'.
Most of the time you flop something - like a pair - you have to jam lot of single pairs on the flop 100 deep.
For example AJ82 on 942r is a insta shove.

4betting: yes it is often 60/40 PF, and creates massive variance, but it is enormously profitable.
You crate big pot with 10% equity advantage, then on the flop:

1) if you hit - pot (or bet small on dry boards)
2) if you miss and board connected, like T94ss then check behind
3) if you miss and board is dry - bet 1/3 pot.

This is PLO, variance is inherent in this game and there is nothing you can do about it.
Correct response to this guy strategy is to 4bet a ton and also jam over cbet (assuming he cbets often) a ton too.

Look - his range is much weaker than yours, so what are you afraid of?

There is another way to think about it
if you play .5/1 100bb and he 3bets 100%, then this is almost equivalent to playing $1.5/$4.5 with like 12bb stacks.
In such game you would still be raising like 50% buttons, and limp lot of other hands (which is equivalent to raise/calling in .5/1 game)

This isn't somebody 3betting 40%, but 100% - there is huge difference.
Embrace variance or you won't get far in plo.