Hell, a little salty language and telling people they're being idiots when they are being idiots is not a bad thing. The best machinists and millwrights I've worked with were like that, and it was a good thing - you don't have time to ask politely when there are steal beams or a two-ton electric motor swinging towards you.
C can be almost as dangerous :-)
The rational is that you should only be working on systems-level code if you have an exceptional understanding of computers, the code base, and the repercussions of changes. If your understanding of multithreading isn't flawless then you should not be working on the OS scheduler, at all. And for a programmer working at this level to not recognize the importance of code clarity is to undermine the responsibility that goes with it.