I think this is a counter statement; one statement invalidates the other. "When he checks i expect him to be fairly weak. Is it better to take a free card OTT and realize our equity?"

If you think when he checks he is weak I would be betting small. It will tilt them to fold for 1/3rd pot, and you can get some calls from some crushed hands or others calling to effectively chop against the wrap components of your hand. If he does fold you can develop a dynamic where you get a really good price on some light calls postflop to bluff turns when he checks.

If his equity is 5% and you check, his equity realisation is 100%. You have charged him nothing to realise his 5% equity.

You shouldn't be too worried about letting someone with 5% try and realize for free. The trade-off to letting them realize that marginal equity "for free" is you can effectively bluff catch rivers which, if they are aggressive at all is more +EV than just betting and them folding. But nobody only has 5% in PLO even with one card to come

This hand looks perfectly played to me, especially against a player with the stats you mentioned. Against some more balanced/tricky players you may have to worry a little bit about getting X/R on the turn which would kinda suck at 200bb deep, but still not that much that betting is not the most +EV play on the turn.