Senior hockey leagues normally don't feature a lot of rough play, although it does depend on the guys throughout the league.
Although this hockey league caters mostly to middle-aged players, this particular brawl was probably unusual for the league.
A combination of a strong punch and the opponent losing his balance caused the battle to end quite fast.
I believe that fighting is acceptable in senior leagues. Fighting is a natural component of playing hockey. All I can say is, if you aren't wanting to start a fight, don't do anything to start one.