There really isn't any logical reason for not making it your responsibility to help the person out, you fucked up, didn't use your brain, end of story. Learn from it, and do better next time.
The spirit behind this statement might be valid. However you are speaking from a place where you simply don't understand the real world. You've never ventured out of your safe little area of Wells, Ogunquit, York, etc. You don't know what it's like to be in a true urban setting in the circumstances that Dave was in. You could get away with something else outside of Federal Jack's in Kennebunk. Dave was in a slightly different setting and, key phrase: Didn't know the area. I appreciate your sentiment. I believe it's off tune a little.
I'm 6'2, 240 and hold several different black belts in several different forms of martial arts. *I* wouldn't have laid a hand on the guy and *I* would have been tempted to walk away. Raptor, have you ever dealt with someone under the influence of meth? Coke? Heroin? Dave have no way of knowing what the guy was on. Where the second wind could come from. If the guy's friends would come around the corner, equally strung out and think Dave was trying to mug their friend.
There are times that you need to worry about your own safety first. Personally responsible and individually accountable. You SAY you would act different. Why don't you and I take a trip? We'll go into Southie, I'll drop you off. You WILL encounter someone in this condition. I would like to see what you would actually do. It's easy to cast stones from the safety of your living room while on line. It's harder to actually have the conviction of your words and act the way you think you would act.
You do you and stop judging others. I think you might be more balanced over all once you figure that out.