I don't think it's that bad when discrimination exists in a fiction world.
It's just one form of obstacle a MC has to overcome in a story.
But it has to be implemented with a bare minimum of realism.
Here, the school is supposed to ignore social classes during the entrance exam.
However, the headmaster here made a clear, textbook case of discrimination, and he orders it with pure authority. No explanation (e.g. "our funding relies on noble patronage"), nor bargaining (e.g. "we'll fund your basic needs and give you a grant for research, so keep quiet and stay low"). And there is clearly no misunderstanding. They both know that he is exceptional, and they both understand that he will be ranked "weakest" purely to accommodate nobility. With a clear visual indicator of his official rank.
(It is even more inconsistent as they established that the nobility in this world is way less influential than in other works. We can't just ignore that other bit of idiocy.)
The MC has literally zero reason to accept this treatment. On the other hand, getting the scholarship would fulfill several of his objectives. (Immediate needs + research environment.) He is clearly way ahead in scholarly knowledge already (not so much with everyday common sense), so he's not here for actually learning magic like a random student. He could walk out very publicly and go sign up at another academy. First, because distance is not an issue to him. Second, because he knows how exceptional he is. To him, it would be a minor setback. To the headmaster, this would be the biggest loss in all the history of manga headmasters. And yet, the chapter presents things as if the MC is the one at a disadvantage for some insane reason, and that's after clearing out the common cliche of "misunderstanding his own power level".
That is the problem I have. None of these behaviors make the least bit of sense. The story is already broken, and it was on a shaky foundations to begin with. This is the one thing I can't stand in my readings. I can forgive below average art, generic story, predictable outcomes... but broken consistency is the one thing that I can't compromise on. Because once it's broken, nothing in the story matters.