Assuming there is contact with the hand, we do have the idea that a hand above the head is likely a HB. (I’m too lazy to look it up, but wasn’t that one of the specific items in IFAB’s awful checklist that was in the Laws for a year?)
Despite the sales pitch that VaR would reduce controversy, we again have a scenario that would have had minor whinging from Celtic fans about a no-call pre- VAR that becomes a major controversy via VAR. (And it would have been a bigger controversy had VAR not acted than it would have been pre-VAR.) but the genie is out of the bottle and never going back.
It would be interesting to hear the discussion in the booth and with the R. Did the R start by saying something like “I’d have a HB if it touched, but I can’t tell if it touched.”? Did the in booth discussion start with, the hands up there, but doesn’t look like it hit, so let’s check that, and focussed so much on finding contact that he never re-foucssed on deliberate/biggering?