One simple question. How do report on something you did not see or saw and deemed not serious. A second by second match report written after the event is impossible. So the question must be asked directly. Eg did you see the elbow on Reid? Is different to - was the clash with Reid serious. If he answers no to the first then it is referred. If he says no to second it is let go. The nature of the question and who asks the question is all important.
Challenges that the ref is clearly looking at should not be re-reffed regardless of what he may have missed or how he interpreted it. It's farcical.