Based upon your feedback, I've looked at the incident again on video, at the appropriate law and the ref guidance.
The law says:
Challenging players in the air - Law 10.4(i)
Play on – Fair challenge with both players in a realistic position to catch the ball. Even if the player(s) land(s) dangerously, play on
Penalty only – Fair challenge with wrong timing - No pulling down
Yellow card – Not a fair challenge, there is no contest and the player is pulled down landing on his back or side
Red card – It’s not a fair challenge with no contest, whilst being a reckless or deliberate foul play action and the player lands in a dangerous position
The ref guidance (April 2015 - Laws Representation Group) says:
Challenging players in the air - Law 10.4(i)
The options given were:
Play on – Fair challenge with both players in a realistic position to catch the ball. Even if the player(s) land(s) dangerously, play on
Penalty only – Fair challenge with wrong timing - No pulling down
Yellow card – Not a fair challenge, there is no contest and the player is pulled down landing on his back or side
Red card – Not a fair challenge, there is no contest and the player lands on his head, neck or shoulder
Based upon the outcome, the laws and the outcome (unlss I am using outdated guidance) then it has to be a red card. While NO noted that he thought the impact was shoulder, the law and guidance don't appear to change the direction that a RC was the appropriate route. That said, the footage from various angles show head and shoulder hitting the ground together. Kearney having his eye on the ball is immaterial because he was not contesting for the ball.
L'irlandais, for clarity I was not disputing the outcome of the game, simply seeking views on this one incident; as with any game, there was plenty of scope for dialogue on other issues. I thought both coaches comments on the incident were reasonable with Rennie noting; "I'll let officials decide that sort of stuff" when asked about the incident and recognisng that Warriors were not clinical enough which seemed reasonable.