... why I thought the one small person who rushed me unarmed represented a threat of death or grave bodily injury, I don't know how I'd answer that question.
"Because he had thrown something at me and was part of a mob."
Precisely because he was part of a mob. All he has to do is slow me down enough for more mob members to arrive so the grave bodily harm can commence.
And that's the way I view it. How does that play out in court though? I would assume something like this had played out in court before, but I can't dig up any case law.
Would it ever be legally permissible for a citizen to try to disarm a person he perceived as a threat? What about detaining the perceived threat until LE arrives? What might the members of the "mob" say if they were to testify?