That's not a similar claim. Anyone can be annoyed by anything; the idea that it's "unscientific" to state that a method of recognizing English by measuring the positions of the lips, tongue, and jaw alongside the activity of the larynx will apply to every other spoken language in the world is ludicrous on its face. It will, because those measurements capture nearly every dimension of phonetic variation that exists. No one could believe otherwise, except apparently for metabagel.

Is absolute belief in one’s one ability to estimate how every human language could possibly work terribly scientific?

Me, I like scoping claims to what is measured.

You say that like no one's ever bothered to measure what kinds of sounds can be used in human languages.

The opposite is the case; this is not a lightly studied field.

It's scientific to say other languages are "predicted" to show similar results, but unscientific to say we know they do.