I can see what you're getting at in your comparison of the two cases. However, because the police were wrong not to respond to the serious complaint in the second case doesn't necessarily mean they were wrong to arrest the lad over a comparatively minor misdemeanour in the first case.
Yes, throwing a cocktail sausage at someone has comic overtones, doesn't it? Not so comic if you're an elderly person on your own and a youth unexpectedly hurls a missile at you. Could be quite frightening I would imagine. It obviously disturbed the gentleman concerned enough to make a complaint, so perhaps the police were right to arrest the lad.
I also never threw missiles at elderly people when I was a kid, but then again, I'm just "a fool".
