I think you could easily argue that in his mind he had to exert such force on the first male to ensure he was not going to be a further threat in order to move to the first male.An angle I and probably most wouldn't have considered. There is a lot to it and all happens so fast. It is certainly not as simple as a basic loss of control or temper.
Indeed, he does that. It’s violent it’s potentially v dangerous but he stops the first male. The taser whilst temporarily incapacitating him was not a guarantee to do this. This was a deranged and out of control violent individual intent on doing untold harm to the police.