Doesn't look like his back to me.
Would agree the red would have been a bit harsh just for the tackle, it was the fact the ball had long since come loose, the tackle was complete and the ref had stopped the game before the spear tackle was put in. Deserves the red.
The high shot that got Gregg stretchered off he holds his hands up straight away but he definitely went for Gregg after the ball had gone. Think he intended to take him out but not high, ended up getting him right across the neck which is why it was so bad. Deserved a red.