Benn was assessed a five minute major and a game misconduct on the play, and should also face supplementary discipline from the department of player safety.
It's a play that simply dials up the aggression to an unacceptable level, towards a clear intent to injure. If the department of player safety is at all competent, Benn will be suspended with a harsh sentence to discourage such reckless plays.
Benn was perhaps trying to find a way to spark his team, being down 0-2 to the Vegas Golden Knights and likely to lose the series. In the following minutes past the play, Vegas was able to score three times in the first ten minutes. If Dallas can't win both games at home, they'll have an uphill battle towards the Stanley Cup Final, hindered by the absence of their captain.