It's startling, to say the least, to see Wideman absolutely staple Henderson on his way to the Calgary Flames bench. Wideman had received a brutal hit just moments before and seemed to be dazed while heading back to the bench. It's hard, perhaps impossible, to say what exactly was going through Wideman's head at the time of the hit — he claims it wasn't intentional.
The NHL either doesn't believe the defender's story, or decided that regardless of intent action needed to be taken. It appears to me that either Wideman knowingly went after Henderson or he legitimately thought the referee was a Nashville player. I buy that his mind wasn't all there at the time of the hit, but he absolutely went through the motions of laying a hit.
Regardless, the Flames will now be without the defender for the next 20 games. Calgary is scheduled to play the Sharks twice in that time, meaning that barring a playoff matchup (lol), San Jose won't see Wideman on the ice again this season.