Yes it's true, his first responds isn't "this is a piece of shit". It's "YOU are a piece of shit".
Here is the C++ rant: http://thread.gmane.org/gmane.comp.version-control.git/57643...
As far as I can see, that was his first post to that thread. He said his target was "full of bullshit", then proceeded into a rant about how C++ programmers are so bad he wants to deliberately keep them off his projects by pissing them off.
I think it's a good example because there are plenty of criticisms of C++ one could make but Linus does a terrible job of putting forward those criticisms. He seems to be so blinded with rage that he can barely form a coherent argument.
Additionally, as far as I can tell the people involved here were not old timer core git contributors, they were new people making an honest attempt to contribute, so the argument being put about that he only targets old hands who have a thick skin isn't true.