All items that can plausibly be weapons, and used dangerously. As others have pointed out, though, had he been carrying a .223 rifle with a 30 round magazine (an objectively more dangerous object) I can't imagine you reaching the same conclusion.
Why is a guy with a fused (but apparently not filled?) pipe bomb presumptively a "criminal" but a guy with a rifle not? Doesn't that have something to do with expression? Shouldn't that distinction be presumptively respected by law enforcement?