Yeah, after reading through, those articles equally contain cognitive dissonance. From how I read it, it’s ableist to insult intelligence because intelligence is primarily a proxy to insult mentally handicapped people, and because its criteria are largely arbitrary.

What about doing something unwise? Touching a hot stove, poking a bear, trying to jump across a wide gap you’re not sure you can make it over, these are not good ideas. The thing is: the criteria for what is “wise” is equally arbitrary! The arbitrariness of a socially-constructed idea are less important than how important the cultural zeitgeist deems the idea to be. Most socially constructed ideas have arbitrary criteria because their definitions are not strict, that alone is not enough to dismiss them outright. Their harm to the mentally handicapped could be, but I see this as a red herring to solving that problem.

Policing the language used won’t prevent them from being insulted for being mentally handicapped. People will just make up new terms, as has happened time and time again. If it becomes blasphemous to insult intelligence, another proxy for it will appear, and that will be insulted instead. They’ll insult the unwise, the foolish, the unprepared, etc. In my opinion, the attempt to stamp out ableism as you’ve described it is a thinly-veiled attempt to try to prevent people from insulting each other at all, which, while morally virtuous, is rather naïve.

Then ableism will never die. What you are requesting be done is absurd. People say things they do themself are stupid, “I just touched a hot stove without thinking, how stupid of me”, they of course would do the same to others. If that’s the correction you want, you’re going to be in the vast minority and will be fighting a losing war against core fundamentals of human behavior.

What alternative word would you use in this case, as a pejorative insult to someone’s intelligence?

Looking at the list you’ve provided, they’re all generic insults not specifically aimed at someone for doing something dumb. If the problem is that the pejorative is aimed at intelligence…ableism will never go away. People will always insult the intelligence of others when they do something dumb.