It’s not reasonable to shoot someone who is walking round a store with a loaded gun, in an open carry state, simply for doing those things, so it can’t be less reasonable to shoot anyone else.
As to whether it’s equally unreasonable, or more reasonable, depends on the specific circumstances. Someone who’s been told to freeze by the police, but then gets his wallet out, that’s reasonable. Someone running away, as discussed before, depends if they were an imminent threat before they started running away. Running doesn’t automatically negate the threat, again it depends on the circumstances. If it’s the case I think you’re talking about, the claim is that he was never a threat in the first place, not that he stopped being a threat by running.
Dunno about the case with the stapler, I’ve never heard of it.