Rushforth has argued that Read may have also touched the ball. That may be correct, but it is far from C&O. However, he also argues, in the same breath, that it was not a fair contest. That is an obvious logical disconnect; if its not a fair contest then you have no chance of getting to the ball, but if you touch the the ball on then you must have got to it. You can't argue both claims to be true.
It was The Fat in post #9 who had the good video and asked whether it was Read knocking on. But as you say, it is not 100% clear from even this video, never mind in real time.
As to an "obvious logical disconnect", perhaps I should have used the word "alleged" twice in the penultimate paragraph of the relevant post.
Remember that my first impression - from a very poor video feed - was PK against Black #8 for dangerous play. Remember that at the time the whistle went, a Black player had the ball and was behind the red defensive line. The quick whistle reinforced my belief that a penalty would be forthcoming against Black #8 for foul play, rather than for an immaterial handling of the ball by Red #16 while advantage could be played.
However, on viewing this better feed, I find it not unreasonable to at least consider the possibility that it was in fact a fair challenge by Black #8, but if he did get a hand to the ball, then the question was raised by The Fat of whether it might not be a knock-on by Black #8 instead. Certainly the ball continues to travel in the direction of the opposition's dead ball line, from the Black perspective.
In Boolean algebra, there are AND and OR operators. There is also something known as the exclusive or, XOR, which is appropriate in this case. It can be thought of as "either-or-but not both".
You are quite correct that:
EITHER Black #8 didn't get a hand to it, so it isn't a fair contest and therefore a penalty against Black #8;
OR Black #8 did get a hand to it, so it is a fair contest and therefore knock-on advantage to Red if it went towards their DBL.
I fully agree with you that not both can happen, and also that it isn't C&O which (if any) did.
What I do not agree with is that Red #16's reflex reactions in first instinctively grabbing the ball and then dropping it in the misguided belief (created by the momentum of the ball and even more by that of Black #8) that he was off-side are a C&O PK offence.
Apparently it was Warburton who suggested looking for the accidental knock-on - very diplomatically - and this perhaps allowed Poite to save face, not completely reversing a decision which he had no reason to miss from the kick-off.
I'm happy with a scrum either way, both as a referee and as a supporter, but if Black #8 didn't get a hand to the ball at all it would have been an absolute howler to give a very kickable penalty the wrong way.