My read of the note is that ALL NEGATIVE IMPERATIVES USE {Qo’}. In addition to that, some imperatives might also have one or more {-be’}s. I don’t think you can have an imperative that has {-be’} instead of {-Qo’}.
The quoted passage was intended to explain that {HIleghbe'moH} "Cause me to not see" was not ruled out by what's written in TKD.
In that sense, it's not about "negative imperatives" at all. It's about {-be'} being allowed to appear in imperatives when the command is a "positive" one (i.e., an order to do something and not an order not to do something).
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De'vID