Joseph Gresham wrote, “ But when you combine it with the moral justification for self defense there is the constant danger that one will overstep the line. Does one have the right to attack or even kill a fellow human being simply because they look threatening? Does one have the right to kill a young man of colour for suspected weapon possession even though he would only be exercising his constitutional right? Does one have the right to hurt a person because one finds his very thoughts a danger to oneself?”
I think you need to examine what “self defense” means. It means “defending oneself from an attack.” If there is no attack, there is no action that can be justified as “self defense.”
The answers to your questions then logically follow. Attacking someone because he/she looks threatening to you is not justified, etc.
Ahimsa means not initiating harm. It does not mean passivity in face of aggression. The moron Gandhi was one short of a full pack.