Cameron careered into the umpire due to his carelessness in not watching where he was running. Others get fined or suspended for minor umpire contact, so I see no reason why Cameron should escape sanction merely because he gave the appearance of caring for the umpire after the collision, as you have suggested should be the case.
If you look at the wide angle and see where the umpire is running in from, it's as much his fault as Cameron's which is why I suspect they didn't even fine him