That interact and is friendly with practically everyone around her.
YES people like that do exist and its not particularly fictional. Popular people can still be friends/in good terms with those who are less outgoing even without sharing hobbies
He's an outcast cause he don’t interact with people + is socially awkward because of it.
He has no confidence, no friends and is self absorbed in a niche hobby.
In Japanese society it would make sense for him being an outcast and not just cause of the plot
Gojo is a talented tailor, has a hobby that perfectly jives with Marin's, is conventionally attractive, and is 6'1 (as a Japanese teenager).
Only reason he's not already popular with girls is because the (female) author needs him to be an outcast for the sake of the story.
And even then for the initial tweet, the statement "In no way would girls like Nagatoro and Marin be nice to boys like Hachiouji and Gojo" is incredibly reductive for the female characters like wym no way ? I don’t know for nagatoro but marin is a cheerful person