One issue seems to be that these documents do to not differentiate between the "Sponsor" being some other existing PMC or the Sponsor being the Incubator PMC (on behalf of the board). When read from the former point-of-view, they make more sense than the latter.
Craig summed it up:
"...If the Sponsor is not the incubator, then the paragraph you cited applies. If the Sponsor is the incubator, nothing else is required."
Bill's words earlier in that thread are useful:
In another thread Jukka summed it up:
"No ACK needed, as it was the Incubator PMC itself who just voted."
From those words we should be able to add an introductory paragraph in those sections to remind.