Simply asking for someone’s wallet is not an infringement upon their liberty (at least not in the strict sense of this scenario), so what is the crime?
It doesn’t matter if you get on one knee and ask in a very nice manner for someone’s wallet if you are still pointing a gun at them. In this case, you are again giving the appearance of having the intention to inflict injury if the victim doesn’t agree to give up his property.
I don’t like this scenario. There will be some disputes over choice of language but, I’m not sure that someone has the right to feel threatened if that threat translates into coercion. To feel threatened is of course subjective and conditional on many levels of the human physique. But it would be considered positive obligations on our part to guarantee another human being not feel threatened by our action or to cease an action because another human being feels threatened. Given this, I know there are some extreme situations where this theory would seem a disappointment, like the one you mentioned where a gun is being pointed. Even this, I believe I have a solution (as arrogant as that seems).
Under a theory of Absolute Rights to Property and Explicit Contracting (though longwinded, see here and here) i think we could eliminate the bulk of these loop-hole-thought-experiments.