it's much better to never 3 bet than to just 3 bet AAxx. It's also terrible to expect anyone to be running a HUD/thinking at .02/.05 and or try and get them to fold trips since you must have have top full.

If you want to play 9/6 I'd play LO8, not PLO. If for some reason you insist on super tight PLO, 3 bet 100% of the hands you're playing.