Can a maintainer really NACK any patch they dislike? I mean I get that Hellwig said he won’t merge it. Fine. What if for example Kroah-Hartman says “whatever, I like it” and merges it nonetheless in his tree?
Yes, but asking him in this case was basically a courtesy, the code isn’t going into anything he manages. He can reject it, but that’s an opinion, not a decision. It can still be merged if the regular maintainer (or someone senior like Linus himself) approves.
Can a maintainer really NACK any patch they dislike? I mean I get that Hellwig said he won’t merge it. Fine. What if for example Kroah-Hartman says “whatever, I like it” and merges it nonetheless in his tree?
Yes, but asking him in this case was basically a courtesy, the code isn’t going into anything he manages. He can reject it, but that’s an opinion, not a decision. It can still be merged if the regular maintainer (or someone senior like Linus himself) approves.