So, to be clear as to the outline you present: Mauro made one ill-advised comment on the bug, and Linus shit all over him? No "Mauro, you're wrong and here's why", no "Hey Mauro, you need to remember that we don't break userspace apps, regardless of where we think the bug lies". Just zero to SHUT THE FUCK UP.
That's the problem here: Not that Linus corrected Mauro, but that he exploded in a rage. A more temperate response would have resolved what really was ultimately a miscommunication.
BTW, you leave out Mauro's longer, more detailed response for where he lays out a good case for understanding whether or not there's a userspace bug in play because it explains why the tests didn't find the regression. Linus assumed Mauro was passing the buck; Mauro was actually trying to track down where the process failed. But that doesn't matter, does it? We're geeks, we're socially efficient. And if Mauro now has a giant black mark of Linus shitting on him, well, it doesn't matter if Linus was right because that's how we roll, and the rest of the world is wrong.