Checking again it appears that they're all still there, so it's not the case that even if they were set to flush via a later chron job that that event got triggered (or certainly not within the last two weeks).

I'm tempted to cut the storage time for feeds back to one month which will put them well within the time frame to try to get rid of them that way instead.

Out of curiosity as I don't see it documented, when the system flushes items longer than the "Months to retrieve and retain feed items", does it delete everything that hasn't been drafted, or does it keep items on which actions (star, comment, nominated/drafted) have been initiated upon? I ask this because for those using PressForward as a self-hosted version of webapps like Pocket/InstaPaper (which both you and @mAAdhaTTah appear to), this would be a very useful feature without needing to take the additional steps of nominating/drafting the particular post. Further, does marking as "read" save the date/time as it may be useful to have this data? (I looked around and didn't see any fields which would have indicated this as a potential feature.)