I think in this instance is a bit different, we are talking about reaction in this case to the supposed aggressor. I won’t lie I am guilty of this myself at times, but this can also be detrimental on many interactions (depending if we are talking about a stranger vs a friend or family member). To be clear, we as humans are hardwired to always prioritize our well being first, and sometimes that does contradict on how our behavior is expected. However, on every instance of these events we should be able to first think how we should react and then do something about it (on a flight or fight situation this does not exist, since at that point our reflexes and reactions prioritize our well being first no matter what). Meaning, for the most part we should try to behave in a way that de escalates a situation instead of escalating. And for my understating, this is where the kindness argument comes in. If a situation can be de escalated by not responding on the same way as the aggressor, you can potentially get out of the aggression situation to a more neutral ground.

PS: regarding your internalization bit, I cannot say what is the best way to live your life, but from my personal experience, having someone to just talk to about these subjects can be extremely valuable. Just by offloading in a constructive way to someone (meaning, no lashing out) can relieve a massive burden out of you (and as for me, I do not believe in the methods where there is not feedback, e.g.: diaries, but that is my take)