Curious, because in the footage I have (A17V.1465003.MPG), I can clearly see Cernan, and to a lesser degree Schmitt, kicking up the dust which moves in front of them, and hitting the surface at about the same time they do, especially in Cernan's 'hippity hops', where the dust is landing just after Cernan, showing that he's moving down hill, as the dust is a head of him (lining up with the photos of the area).
Yet, we do not see the "airborne dust", but only a shadow at ground level, indicating disturbances as the dust scuttles.
If it were airborne, it wouldn't all fall at the same exact point for 1/3rd of a second.... However, scuttling sand is far more likely to behave like this.... all hitting the same "slightly high point".
I'm OK with mostly dropping this "Sand falls to fast" issue, and putting it at the bottom of my list -- mostly because it's the most ambiguous and leaves too much room for people to "see what they WANT to see" -- similar to saying "what do you see in those clouds?"
The chaos of dust, seems to work in a similar fashion here. This is not a good point to linger on.
Compare this to other 3 points - where we are talking about a very well defined singular object (e.g. the flag, the AM, the A12 Dish)... so will stick with those.
To me the sand falling too fast seems painfully obvious, and cannot see at all how someone could miss it. You seem to feel the same, but with an opposite conclusion.
So I'll just (mostly) drop this specific point for that reason. I won't call it "undebunkable evidence" as I do for the other 3.