[Oatka]

The wannabe probably forgot to blacken the orange tip with a black marker like many do nowadays.
Would that have enabled it to kill the cop?

Of course not, but it alters the perception. The idiot didn't know the guy was armed, and most unarmed citizens wouldn't be aware of the difference - and obey the robber.

Oops!

[ROCKLOBSTER]

Or maybe, he did blacken the orange tip, which if he hadn’t, may have prevented his being shot to death.