Because that is what he is meant to do and he also like.
"[F]or never man had a more faithful, loving, sincere servant, than Friday was to me; without passions, sullenness, or designs, perfectly obliged and engaged (186)." -APEX
The part of Ernest Hemingway's short story "The End of Something" that is the best example of rejection of traditional beliefs is C. when Nick says love is not fun.
The traditional belief would suggest otherwise - however, by denying the thrill of love, Nick is getting rid of this innate traditional belief. The other examples do not really show this type of rejection, they represent other things that can be found in the story.