"....Forum postings from DMOZ editors suggest this is completely wrong – that the process works perfectly and submission success is always emailed ...."
That statement is, so far as I've ever seen, a pair of false representations.
(1) that e-mails are sent out on "success" of a "submittal". They aren't, they never were, and I've never seen a real editor claim they were.
But, beyond that, from an editor's point of view, a submittal doesn't "succeed" or "fail". It simply provides information that turns out to be useful or not useful. (Sometimes it leads to the information being passed on to some other editor, or to other information being gathered, or even to some other site being listed. But for us it's always "we received some information, we made whatever use of it seemed most helpful to our users."
(2) "The submittal process works perfectly." When people are involved on both ends, I can't imagine believing that, even if someone told me so on a stack of Bibles, and even if I didn't know better of my own experience, which I do.
Based on my own experience (including several systematic re-checks of fairly random sets of submittals) I think the error rate is something like a fraction of 1% for inappropriate site rejects based on submittals, and several percent for inappropriate site listings. I have never kept those estimates secret.
It would be fair to say that (1) the submittal process works better than anything professional submitters have ever suggested, possibly could have (which is extremely faint praise); (2) the submittal process could not be improved and would certainly be harmed by giving additional weight to professional submitters (which says more about the depravity of many professional submitters than about the quality of the editors' work), (3) the ODP would be harmed, and would not be improved, by giving more priority to the submittal process, (4) we have never seen SYSTEMIC problems with the submittal process (which is what a sane person would need to see, before thinking that any procedural change is needed), (5) we have never seen problems with the submittal process significant enough that systemic re-review of rejected sites wouldn't be a major waste of time, compared to anything else the editor could have been doing, (6) even in its imperfections, even under the spam, the site submittal process still "works" (for the only purpose that it was ever intended to fulfill): that is, it occasionally provides some editors with enough useful information that they think it's worthwhile to keep it.
Sometimes, people who are think they know everything translate "you think your way is better than my way" into "you think your way is perfect." Which could only be logical if THEY were perfect. Which very few people are, in my experience. So that's basically never a correct translation. If an editor thinks the ODP as it now is, is better than a suggestion, it's usually because most of the suggested procedural changes are so utterly brain-damaged and misguided -- not because the ODP is perfect, but because just because some spammer think he's Napoleon doesn't make him emperor of his own asylum, much less the sane part of the world.
So, charitably assuming the guy isn't lying for the fun of it, he knows so little about France that one wonders why even the other asylum inmates think he's Napoleon.
I doubt if your site was rejected, it is more likely that no one has reviewed it yet.