I relate to all of what you said. Just some thoughts of mine:

"A narc or someone else with other issues may accuse you of being defensive even when you are debating calmly and logically. Some narcs use the defensive card to throw you off and/or to belittle you for disagreeing. Unfortunately, growing up with this constant negative feedback can make Acons feel more vulnerable when asserting themselves, and so some of us do tend to feel overly emotional and thus defensive."

I do wonder if the person accusing me of being defensive is trying to dictate how I should feel and think. IMHO, I think people have the right to express themselves as long as they're not harming anyone. Some people naturally tend to be more passionate when speaking or writing.

"However, another Acon tendency seems to be to over-justify a decision or opinion. It takes some experience to realize that most decisions don't require much or any explanation. The average acquaintance doesn't care why you bought black jeans instead of blue, for example. Instead of stating XYZ, just X might be fine, or nothing at all, especially after the argument has been won. Surely I'm not the only Acon to retroactively justify a decision! "oh, yeah, since we all agree because of X, well, here's YZ (just in case it's a trap)"...nope, it's done, nobody really cares, and move on!"

I have done this too, but am learning that it's not necessary. Healthy people that respect your boundaries don't need to know why you did something, and don't need to demand personal information. I have had other people in my life (other N's, bpd's, sociopaths or nosy female acquaintances) want to know why I did certain things. It just got uncomfortable having to justify my decisions, and made the situation worse. Because, most people aren't going to validate or understand anyway (IME).