Linus is dead wrong here. When he says acting professionally means "fake politeness, the lying, the office politics and backstabbing, the passive aggressiveness, and the buzzwords", he's attacking a straw man: none of that behaviour is professional, and to say that professional behaviour must degenerate to that behaviour is a stretch at best. Aggression is not warranted in a professional environment; neither overt (a…
So what is the profesional way to refuse to work with somebody you don't want to, or to mark the work of somebody else as bad? Of course options that will require a lot of time are not good, like gently showing how a "few" things could be improved.
Leaving out the reasons would also be ok, but don't be surprised if this results in confusion and anger. (However, the abusive alternative to this will likely not help reducing the confusion or anger.)
"This work is bad because of reasons A, B, C."
Leaving out the reasons would also be ok, but don't expect other people to agree with you if you do that.
Being straightforward doesn't require one to be abusive.