It really makes me wonder what is going on at Bath when nobody there seems to think this incident was a red card.
Commentators at the time said he was hard done by as he hadn't actually made contact with the head. It was a team mate he drove into that inadvertently did.
Fair enough, that shows he didn't mean to do it. However, if you approach a breakdown at that speed and angle for a clearout it is most definitely reckless and likely to cause injury, which it did. Therefore clear red card.