In context it was fair because I was responding to a situation that was already playing with the definition, and once you allow that you have to allow taking it all the way.

Unfortunately, I started my reply to the wrong comment and didn't notice until after I'd posted it and it was too late to edit/delete.

tl;dr too many people have a knee-jerk "security through obscurity!" reflex action to things they don't like, and I have a reflex action of yelling at them about it, which sometimes misfires when I don't take care to reply at the right point in the thread.

Agreed. Kerchoff's principle isn't really up for debate.