I'm not wrong, you do not need intent to prove a manslaughter charge
Just a scenario as I have no idea if this is a thing in Ice Hockey or not. Say there are rules of the sport about the skates and the player who kicked the poor dead guy in the throat had done something outside the rules to his skates (a bit like players used to do to studs on football boots), if it can be proved that that grossly negligent act resulted in or contributed to the death of the player, then this would be a case of gross negligent involutory manslaughter. He didn't intend to kill or harm anyone but his actions still resulted in the death.
I doubt that's the line being followed (or even if its a thing) but it's just to illustrate the point