He probably was put on a course to train him to behave that way. The problem is that serious aggression is such a common trait in us Irish that he has to go in aggressively so as to get his retaliation in first.
If he goes in all nice as pie, people will just walk all over him so he has to be seen in the first place as being unwilling to take any crap from anyone. It is exactly the same everywhere with ticket inspectors - there is no other way to get the job done.
I reckon he'd want to be wearing a stab-vest the way a significant minority behave in this country.