Nothing I can recall illuminates the issue further. But there are a lot of documents in the collection, and I have read only a fraction of them. It is worth pointing out that Justman wrote or dictated many, many memos -- so the fact that he did so here doesn't suggest any departure from his normal job duties.
My speculation (and that's all it is, really), is that some review of the dailies had been handled by Gene Coon. (Perhaps Gene Coon is the one who reviewed TDM footage.) After Coon left in September, 1967, more (all?) episodes were reviewed by Justman. There's no memo from Justman about Decker's patch in TDM because Gene Coon was the one who reviewed *those* dailies.