So what you seem to be suggesting is that these guys had some strong incentive NOT to push an attack on somebody, given all the witnesses on the scene that could ID them.
Criminals routinely get linked to unsolved crimes when they are arrested for current crimes. Fear of being linked to one crime is not and has never been a deterrent to commiting another crime.
As for judging people, it's great to recognize that most of us haven't been in situation A or situation B. It's great to acknowledge that we are arm chair quarterbacking.
It's important to acknowledge that both of those facts will apply to any judge or jury (and even many investigating officers) who will do the same thing if we are ever in such a situation.