His worries seem legitimate even if he's to this point been portrayed as a huge asshole. She's going to a school that's well below her actual ability because she wants to be around her man and live a normal high school life. Obviously that's her choice at the end of the day, but MC could potentially influence her to pursue greater academics and still get to be around him for the most part since she could go to school in Tokyo. I doubt that's what she'll end up doing but its not a baseless concern her brother has
Yeah - it's unfortunately a balance against the fact that you mentioned - he
has been portrayed as a major asshole, and that instantly colors his request here in a poor light due to his established character.
The fact he relented on the Tokyo school option is really very surprising, because it's almost at odds with how he's been up to now.
The remaining issue, is that I
do see MC simply deciding "oh, I
am holding her back", and then just tells her to go to a better school. And she'll misinterpret that as him telling her off/
calling their engagement which will cause her to spiral (for once, her being the one confused by the subtext).
Feels like a "Third Act Climax" sort of deal, honestly.