Yeah, I personally would hesitate to offer patches or analysis to lkml, simply because I don't want to be part of a conversation with that tone.
For what it is worth, it sounds like Matt Mackall stated a plausible threat -- that an attacker might be able to predict results from get_random_int(), thus being able to predict the address space randomization that is supposed to stop him. Linus's reply as quoted in this article, saying that Matt's concern is "TOTALLY INSANE" doesn't make sense to me.
I don't think that any cryptographer would ridicule Matt for this concern. To the contrary, I've always observed cryptographers (the vast majority of them) to be polite and precise. Engaging in ridicule leads one to make mistakes. ;-)