The fact of the matter is that one can just as easily be a brash and insulting bullshitter, or a friendly and polite straight-talker.

Yes it is possible to be so, however, it is not always possible to know if a friendly and polite person is a straight-talked or a bull-shitter - the advantage of Linus' personality is that there's is absolutely no question which one you're dealing with. I wouldn't recommend this as appropriate behavior when dealing with unknown people on a new project, but for a long-running project like Linux, I can't imagine most people can't unemotionally disregard Linus' language as "just the way he is" - if he was the type of person who if you were to disagree with him, he would then try to destroy your career to teach you a lesson, now then I think you'd have good reason to condemn him. I personally have no idea how he handles disagreement though. In my experience, I'll gladly take a harsh but righteous person over a polite politically-savvy self-promoting bullshit artist any day of the week....these people are a lot more common than many people think.