I'm in no way defending what these assholes did. I think they should have the book thrown at them.
I'm told from a very credible source that the homeless man they killed wasn't a mind your own buisess down on their luck feel sorry for him kinda guy. He was known for being aggressive, violent and attacking people passing by in the street. The kinda guy you cross the street to avoid.
Mix a violent agressive homeless man prone to physically harassing people with some young drunk men full of stupid passing by and, atleast I think, the randomness of the assault becomes a little more clear.
I was also told a day after the mans death his estranged wife whom apparently had not seem him in years, showed up at the armories shouting screaming an demanding money.
Still no excuse for what they did of course.