I don't see how you can argue that Cane is a red card. We are to often guilty of looking at every at plays in super slow-mo and dissecting every minute movement of the player as though in that fraction of a second it was an intentional act. These tackles should be looked at in fullspeed.
If you watch the Cane tackle at full speed you'll see he made his initial move to engage the Irish player and the green player bounced off another NZ player and that changed his trajectory. A fraction of a second later Cane's arm makes contact with him and it is around the shoulder area. Unfortunately the Irish players head makes contact with Cane's shoulder. At full speed you can also see that Cane is making an effort to use his arms in the tackle, with initial contact being with his chest/shoulder.
It looks bad but I wouldn't card this at all. At most I would penalize it, but even that would be a stretch.
Here's an isolated version of the tackle