I see. Just to make sure I've understood correctly, my impression from this:

sufficient to invalidate your approach altogether, and to conclude that by any practical criteria, your advice is likely to be just noise

is that you do not believe the post is salvageable, because it's built on a foundation which is flawed for the reasons you give. These are useful flaws to be aware of when composing future posts, and I will try to remember them.

If it is indeed unsalvageable, though, I don't see what productive action I can take about it now, short of performing a rigorous study and rewriting the post from scratch based on the results (which is farther than my interest and resources extend). I could delete it, but that seems a bit dishonest (in that it dodges the karma hit for a bad post) and also robs me of productive feedback. So my intent is to let it stand.