If you see a guy trying to kidnap a little girl I would like to think anyone worth a crap would step up and do something.
Of course anyone would intervene in such a situation. I think the idea is that the guy trying to kidnap the little girl is not practicing the action of non-action. There are people who are always stirring up trouble, sticking their nose in where it doesn't belong, themselves in trouble all the time, thinking of ways to manipulate others, imposing their will, arguing, complicating existing situations that are already complicated enough, etc.
This kind of action always creates a negative result. Oftentimes it is better to do nothing and allow a situation to play out as it will when action will only make the situation worse or prolong a conflict. Dealing with events with calm understanding oftentimes is a better method than using some opposing action that will not be as helpful in resolving a situation.