I would say you were over reacting in both ocassion.
Incident 1: I would simply tell the person that " No, because it's a film camera there is simply no advantage having an LCD". I would reply more if the person would ask more. I would rather want to make friend to the person.
Incident 2: I would not do anything and feel good that someone was trying to copy my shot. Nevertherless I don't think anyone can copy my shot even if I tried to explain to them.