It was intentional and a cheap shot. You can see the Utah player start to slow down to absorb the contact. You can see Nelson launch into him with both feet leaving the ground, and you can see the Utah player's head snap back violently. You can see all of that clearly if you don't care about who's playing but do care about player safety. Nelson went for the "light-em-up" hit and got exactly what he deserved because that's the intent of the rule.