It isn't necessarily the decision that makes this a little controversial, but the timing of it. The 5 game suspension (and subsequent forfeit of salary) came many days later after the offending play. The standard reaction time to the NHL front offices is usually 24 hours or less.
Janssen will forfeit $14,248 per game, and the money will go to the Players’ Emergency Assistance Fund.
I think they were trying to scoot this one under the rug because of the recent attention to headshots and physical violence.