Lol..... may be a different story if one of them had been involved. No one can say for sure what they would have done faced with the same events. We don't know how bad the 80 year old was beaten, they probably thought he would die or maybe threatened to come back and finish him off...who knows! It's always easy being a Monday morning quarterback.
I learned a very long time ago, after a traumatic event, that I would be capable of taking a human life. It was shocking to me...but I could have done it.