You have a strange definition of 'retaliation'. If you throw a ball at a brick wall and it bounces back and hits you, the wall didn't retaliate or act in self-defense. The entire impetus and result is 100% on you. The same applies here.
The first use of “retaliation” should be “retaliation and/or self-defense”, like the other. I was staying a broader principle which applies to but extends beyond the immediate case.
I will agree that the proposed device might (if targeted appropriately) be more defensive than retaliatory, though the fact that it only causes harm to the focussed-on target if someone attacks it doesn't make it purely defensive or non-retaliatory, in fact, if not carefully targeted it makes it quite indiscriminate retaliation.
