Pseudophilosophy encourages confused, self-indulgent thinking

I think 'dummy author' has your number. From TFA:

"When challenged, the obscurantist will typically retreat to the safe house provided by the trivial interpretation of his claims, only to reoccupy the controversial ground once the critic has left the scene."

(In fact @fratajcz continuation of Foucault's except in the comment above, makes it extremely clear that he speaks of social truths and their construction).

The author makes a strawman that Foucault here implies something else ("objective truth doesn't exist at all even concerning hard facts"), and then triumphantly declares that it doesn't hold, or that Foucault doesn't justify this claim (which he never did).

In the meantime, he fails to showcase that his strawman was actually meant by the philosopher, or that the intended meaning is a "safe house" retreat.

(Not to mention he fails to see the cases where the "extended" -non trivial- interpretation also holds, e.g. see my answer to parent comment re: history and "facts of the universe").

It's rather the opposite: it's the trivial cases, that Foucault's thesis doesn't apply (of the "fire is hot"/"water is wet" variety, which everybody agrees anyway) - and the more impactful and profound cases (political, social, historical, truth) that it does.

The author seems to apply the inverse prioritization (that challenging "fire is hot" would be the profound non-trivial claim, and challenging "abortion is a crime" kind of truths would be a retreat to triviality. That, though, is because he thinks in terms of analytical philosophy. The former were never the truths Foucault cared about or wanted to challenge.

Even if it isn't evident from the except, Foucault has written extensively about and was preoccupied with, the social truths, on sexuality, mental health, crime, morality. His subject was never the trivial hard-fact truths of the "fire is hot", "water turns to ice at 0o degrees" kind. The author here pretends as if Foucault "over-extended" to them when speaking about truth, to build his strawman.

So no retreat was ever necessary.

It is always funny how long boring sentences are found in philosophy. I think the problem is that our language is lacking in clarity for describing the subtle nuances of reasoning and logic.

And sadly it is a bit confusing. Especially if one (like me), does not know all the people listed in the paragraphs.

Personally I tend to shorten the sentences and focus on the presentation of the information in logical blocks. While it may not read as glorious, it can improve the clarity of the information. Maybe this tendency is related to my background in programming.

What problems did Foucault try to solve?

And I think that your statement is related to the differences in problems that Foucault tried to solve, and problems that we face now.

In his culture people believed that personal traits were related to skull shapes. So the idea that these facts about skull shapes do not really matter, seems very reasonable. Especially we now know that this does not relate at all.

So, the "facts" are related to "beliefs" that give certain values to those "facts". In science we would call those beliefs "models". And while well tested, they have some limits that are relevant.

Pseudo-philosophy or different belief systems?

Some philosophy wants to avoid "facts", here called pseudo-philosophy. But often they do not deny the "facts", but have complete different "beliefs" in which the "facts" do not have the same meaning.

The writer of the article wants to downgrade the "false beliefs" as "pseudo-philosophy". But as a solution, I prefer to look at the limits of the beliefs (or models) that are held on to. This is for both true beliefs and "false beliefs".

Talking about limitations gives an opportunity for dialogs and understanding different sides. People don't feel attacked but feel that they can contribute to mutual knowledge.

And regarding scientific beliefs/models, we may find problems with them, which is essential for scientific progress.