Considering that the conversation was ongoing yesterday and this is an international forum, I wouldn't say that the conversation was "long over." I could have sent him a PM, instead. Then I could have sent PMs to all the people who asked me to look into the issue by telling them that I PMed him. And then I could continue to do so for anyone who continues to report the respective posts, as just happened. And the result would be no different, but it would waste a lot more of my time in the process of not being any more efficient. Indeed, not everyone is "weak-spined" in the way you framed it, but not everyone wants to hear offensively conservative views being projected repeatedly either, and some genuinely forget that the "Ignore" option exists (hence, my reminder that it is indeed an option and should be sufficient for those people). I also could have ignored the discussion entirely and crossed all my fingers and toes that it would never again resurface, but in my long experience on forums (this one and others) that rarely ever happens. By advising someone not to do what they did, it reduces the likelihood that the incident will be repeated in the future, and alters future moderation accordingly.
I'm sorry if the tone of my post did not resonate with you, but you could have "sent a PM" instead of trying to "humiliate" me with a "super unnecessary" post about a discussion that was "long over" (this time it was actually over, as a moderator said "end it" and the respective party said "OK," which is basically the most closure you can ever expect on something like that). If your primary concern lies in not addressing all of the other individual members not to derail the thread, please note that the specific user I addressed was the only one whose remedy required more detailed explanation than "stop". All other users were told to use the ignore button or to otherwise avoid contributing to further derailment through implication, a directive I found to be quite obvious.
Now then, let's go back to costume mods, shall we? I'm still waiting for a banana suit.