It wasn't a full screen presentation. It was only shown in the bottom right hand corner of the screen. The commentators referred to it too, I think. Although, as I said, the ref didn't look at it or seem that bothered by it. But it did look to me like he was caught in the head. Maybe it was the impact of the tackle that led to the HIA rather than the boot to the head.
In any case, I hope he is okay for the Sarries game. I am sure he will be given a rest next Saturday, with Kuanatani joining Chisholm and Dombrandt in the back row.