Rielly drew the punishment for a cross-check to the head of Ottawa Senators forward Ridly Greig on February 10th.
Rielly took offense to Greig scoring an empty-net goal with a slap shot and sent him into the boards in the closing seconds of Ottawa's 5-3 win. Rielly was assessed a major penalty and a game misconduct.
Bettman, who listened to Rielly's appeal on February 13th, has now affirmed all four appeals he has heard so far this season.
The NHL released an 11-page report on Bettman's decision, in which he weighed the facts that Greig avoided any serious injuries and that Rielly has never previously been fined or suspended in 11 NHL seasons.
"Given the nature of the conduct, Mr. Rielly's suspension almost certainly would have been considerably longer if he did not have a clean record of if there had been an injury," Bettman wrote.
Bettman said Rielly's actions were not a 'hockey play'.
"Rather, as Mr. Rielly himself acknowledged, he sought retribution for what he perceived to be a 'disrespectful' act that he believed was intended to embarrass Toronto," Bettman wrote.
Bettman concluded his report by commending Rielly for disavowing suggestions made by others that his actions were appropriate.
"Certainly, the conduct leading to this suspension is out of character with his long record of clean play in the NHL," Bettman wrote. "It is my hope and expectation that the events leading to the suspension were an aberration that will not be repeated."
Rielly hasn't played since the incident, sitting out the last four games (all Toronto wins). He will miss Wednesday night's game at Arizona and is eligible to return on Thursday night at Vegas.
Rielly has 43 points (seven goals, 36 assists) in 50 games this season. He has 457 points (80 goals, 377 assists) in 769 games since Toronto drafted him fifth overall in 2012.
