Okay. It occurs to me we have some inferential gaps that I don't see my duty to fill. Go read HPMOR again, go read some more sequences. This is beginner level stuff, you are not presenting strong-evidence-based arguments, you are asking rhetorical questions, making non-deep analogies and taking things literally.

Is there a "Magic" term is the True Causality Truth? Is there a "Magic" factor in the math from which Decision Theory is created?

There is not a term for "magic" anywhere because first of all, we are arguing about a fanfic, so let us get that mind projection out of the way.

I know Eliezer's core beliefs and messages: He will not allow his work to portray a universe where anything is inherently "magic" because that is bad reductionism. He will maybe not introduce a new kind of quantum mechanics, because it is very much not his style to techno-babble.

Broomsticks, for gods' sakes!

Broomsticks do not conclusively break anything. The speeds are too low for the gamma factor to be measurable with equipment that can function around magic. Broomsticks probably have maximum velocity only in the apparent. Remember, there has not in canon been any precise measurement of the nature of broomsticks.

That the physics is the way imperfectly thinking beings thing is not a credulous hypothesis, because QM and GR are experimentally right, yet counterintuitive, and because the program that describes Aristotelian Physics is more complicated than the QFT lagrangian, for any representation of rational numbers. I know the math, evidently better than you.

Likewise, someone thought that faux-Latin and wand movements should be required to lift stuff with magic, so they mostly are (obviously there was a dissenting opinion somewhere). Someone decided that Seeker was an interesting game rule, and someone decided that Hogwarts need not have a consistent internal layout, so all of those things are true enough.

Have you completely missed the chapter where Harry thinks that the "heart of magic" is a thing the Atlanteans built? In the most recent chapters he thinks about, and talks to Quirrel about how one goes about making a new spell!

Seekers existing does not have anything to do with magic, it has to do with the culture surrounding games. You can see it in many existing games and sports today. Wizards are still human, they have human habits.

Why are we even arguing? I agree to almost everything you say which is not a blatant argument soldier!