Generally speaking, the more important a listing is to the website owner, the less important it is to surfers. Now, this isn't a perfect correlation, but as a rule of thumb it works extremely well.
So the thing you must always remember to do, is try to look like an ODP listing isn't important at all to the website: act in every way as if the site would be a rousing success without anything to do with the ODP.
That is, suggest it once, perhaps suggest it once again after 6-12 months--just like the submittal policy says.