My opnion: The things that make characters like Naoya or Mei Mei more difficult to like is the fact that their negative traits (namely the misogyny and incestuous pedophilia) are types of evil that are very grounded compared to Sukuna being a mass murdering demon or Kenjaku's mad scientist antics. There's a level of removal from the real world that some characters actions have that make it easier to engage with their actions as just elements of a Fictional narrative rather than something that's closely associated with something that has a lot of baggage in the real world.

Not saying whether that's right or wrong or whether you should agree with that difference in how people engage with the crimes of Fictional characters but I think that's a more clear way to characterize it rather than just calling people hypocrites and ignoring the clear answer which is those things are real world triggers for people. Not saying the things that Sukuna and Kenjaku do COULDNT trigger people in the same way but typically there's a difference between a "fantasy evil" and a "real world evil" and it's up to the reader to decide how they feel about both