So what range does the PRO lead out on the flop OOP against 3 people? My most likely guess would be 77xx, some JJxx and also AAxx hoping for somebody to 3-bet. Last but I doubt this more since this is not a hand you want to build a pot OOP but preferbly X/R yourself is KdQdTx. 

If he respects you he might find a fold with 77xx IF you would often 3-bet here with your sets. Does he suspect a flat from you with these hands? The last question how often would you RAISE/CALL with a flush draw here? From my perspective your line looks very draw heavy AXdXdx but as I said before would you often call with sets here aswell? I think you can bet here and quite often expect him to fold all his 77+JJ(some time) depending if he UNDERSTANDS you WILL x with your fd when the river pairs. That way you will NEVER pay off a fullhouse if he now gets so calling OOP with hoping to get it is just dumb. 

Last bot not least do you bluff often in pos and are you capable off floating your opponent. Because he can be in X/C mode with basicly most rivers as you DONT block any FD's att all and villian could quite likely hold KdJJT type off hand which makes the most logical fd for you to have in your range. 

But I personally is a little afraid off betting that turn simply cause donking out on that type off flop when YOU know what you are doing is scary. He could have done it with some draw to get a better price and define your range if he GETS raised. But as a wise man said: position is everything in PLO so IF you bet the turn you have to BET all NON PAIRED( expect AJ ofc :P) rivers to keep representing the nuts. And make him fold Q-T high flushes+ all sets. 

I would personally just X here hoping to see a free river and there decide what to do if he bets into me as I doubt he still going to bet his sets on a blank if you can X the flop with nutflush just to make him do that. There is a chance he is going for X/R with just a KdXXX blocker since that what good players in his position do. Its rare but when it happens you loose a shitload of EV. But I am new to LIVE-PLO so have that in mind. Anyway gave you another view on the situation hopes it makes your analysis better :).