I'm actually sometimes leaning towards just calling the guy's flop raise for reasons other than that - if he has a low set I really don't want him to fold and, in the last year or so, the number of players who'll stack off on ANY set in PLO seems to have lessened (i.e. if he has something like 44xx he may fold to a re-raise). Equally, hands like top two should be kept involved.

This, of course, presupposes you have a read on the guy that he makes "feeling raises" like this with a reasonably good made hand (but one that he doesn't wish to play for all his stack). Without that read, I think pushing is the better move - you can get all his cash in with the likely best hand and ensure that you don't miss out on his stack if the board pairs the turn (to put that factor into perspective - nearly 30% of the times you win this pot, you'll win it by pairing the turn - that means if you DON'T push when he has a draw, you'll miss out on his stack 30% of the time you win the hand). Also, if he has something like 3456r, the flush cards will kill your action (and even give himself some bluffing equity, although if you don't push the flop it must be with the specific intention to push any turn).

So, I only like the smooth call when you have a strong feeling that he's "putting you to the test" with his raise, rather than making the "build the pot" raise with a strong draw. As both are frequent moves for a typical PLO villain, I'd say take your pick . In general, however, I think I'm happier pushing.

How would you have played if you knew villains hand?
btw, I think your line is good. I like how villain played it too, bc
he is out of position and a big favorite over a lot but a set.