While they are blunt and I don't disagree about "him being a dick" written communication is very different from spoken ones, I can imagine someone using such words in a certain context and they sound less harsh.

But in the written medium it really come across is the most harsh way.

But while maintaining the kernel sometimes he needs to get the point across and saying "this is unacceptable, I am disappointed" will not work.

For those examples, when reading the context I (usually) agree with Linus (and with his attitude), and this usually happens when the situation has been building up and people keep repeating those mistakes.

Also, there are people much worse than Linus on the LKML (and subsystem lists), also some people are very polite and helpful.