Since Marc brought up Redwine's temper and since there have been a number of posts about premeditation vs not, I thought I'd throw out my thoughts on this.
MR went out of his way to insure that Dylan did come for his visitation. He wanted it and apparently went to some trouble to insist on it being honored. Then he went out of his way to drive to the Durango area to meet Dylan for visitation.
Then Dylan's flight was canceled. MR had a day to stew about this, possibly while drinking. IF (big if) he was the sort to take everything personally and IF he still had an explosive temper, and IF he still drank and exhibited inappropriate behavior while drinking, then I think these all converged into a premeditated rage.
It is possible that Dylan's frownie in the text to his mom may have indicated his Dad's drinking and belligent attitude on his arrival.
IMO, it is possible. Yes. Did that happen? I don't know. Is it possible? Yes.