well, I have a totally different outlook, but I tend to play PLO extra aggy. IMO I think you should have raised preflop. Your talking about a 6 handed table, with 4 running straight cards with outs to a club flush. In six handed you definitely shouldn't be worried about the nut flush as much as in a ring. You raise it up because if you hit the flop with a deceptive hand like that you want the pot juiced so you can make a sizeable bet and most likely pick it up on the flop or get reraised all in because most likely if anyone has 2 pair its a good chance they'll think your not as strong as you really are
Since you didn't raise preflop, I'd put out a 3/4 to 3/5 bet looking to see who will raise and I'll go all in on that flop. If no one raises and you get callers, than betting on the next street depends on what type of players your playing with. If they're the type that won't make plays on you if you bet into them on scare cards and you think they will try to steal the pot if you don't bet than I think your best bet would be to bet again, if they're deceptive and will call with good hands when they have position with out raising you could check-call, or I like to check-raise a weak bet if your suspicious about it.
The size of the bet on the turn also not only depends on the turn texture but how much money of your stack you can get into the pot and whether you can pick the pot up there. If you think you can bet pot max and pick it up and its a safe turn, there would be the time to do it, but if you can't pick up the pot there with a pot sized bet and you can't let the other players in that pot know that your not leaving that pot than I'd bet 2-3x my flop bet, leaning towards 3. This way if a scare card comes on the river and you are thinking of calling you don't have to call a bigger bet to showdown.
redraws and all that, action or not, if you flop the nuts and you can get all in with no redraw, I think you should do it. For a couple reasons:
1. that situation doesn't really happen often, and not nearly as often as it happens in full ring, plus alot of times is a split anyway. If anything if your gonna worry about it I say worry about it more in full ring, not six handed.
2. IMO that really only applies to the higher limits, at those levels theres a lot more at stake and it becomes alot more obvious that it could be in your best interest to lay down. Much more money at stake to lose, plus the players at higher levels understand that aspect of the game.
3. at the lower levels you have people that'll be reraising you with top 2 pair, sets and draws because they are either LAG, a beginner, or just plain think your weak. You start laying down the nuts to flop action at these levels your gonna start probably getting reraised alot more when the other person doesn't have the nuts and you do, and that could cause you to lose confidence
You couldve also check raised the pot on flop, pending how much of your stack you could get in and the size of the bet you could make. any min bet you could at least 5 bet it. No bets come you can always bet the scare card and try to pick it up there