Good post.

First, what could he have. Worst case he has a low draw with some medium-sized flush (even K-high may be trying to see the river cheaply since OOP, or could be planning to chk-raise). That hand will definitely at least call you and have you in pretty bad shape. Other hands that may call, but against which you have some decent fold equity, include a good wheel-wrap draw like 234, or a K/J-high flush w/ no low. All other hands would very likely fold to a bet here--if not you should charge them for a low-only draw or whatever it is anyway.

So--the question is does the fold equity in the latter possibilities make up for the outcome where you bet & get called/raised by a hand that you will need to river a pair to beat. In general I think the answer is probably yes... If you're against that worst case scenario, you may have to draw with 3:1 odds against making your hand while getting only 2:1 from the pot (if he raises you). Not a good situation. But, that's only -EV by a slight margin. Also bad is when you bet, he calls, the river puts a low out, he leads and you are forced to a tough decision (probably fold). In that case, it's quite -EV. But when you bet and he folds, it's a big +EV. So as long as he will fold a little more often, say about 55% of the time, than he calls/raises you, then betting is correct.

I think that based on the way the hand has been played so far (generally passively on his part), and what I assume to be a strong image for you, you're going to get a fold enough of the time to make betting the right answer.