[zAy0LfpBZLC8mAC]

... when "stupid thing X" is making an argument that doesn't address the problem, and "you can do stupid thing X" is actually an explanation of what the problem with that argument is, and it's also not calling anyone names, but just calling out fallacious reasoning as what it is: Fallacious reasoning? Fallacious reasoning might well be correlated with stupidity, but that doesn't make pointing out fallacious reasoning an insult in itself.

Equally, if the topic of the discussion is what makes a certain decision wise or not, as it happened to be the case here, I don't see how pointing out that a suggested methodology does not qualify due to fallacious reasoning in that methodology is either rude or a flame. That is, unless you consider the start of that discussion (https://news.ycombinator.com/item?id=20129547) a rude flame, which you possibly could, even though I don't think it was intended as such.

[dang]

I'm afraid I'm not really following this. In a way it doesn't matter, though, because even if I missed some subtlety in perceiving your comment as rude, I can guarantee you that most readers would miss that subtlety as well. Since there are plenty of ways to make your substantive points, why not just choose ones that don't straddle that line?