If there was a decline in quality or they needed extra talent I'm sure that they'd probably reassess but that doesn't seem to be the case. Like so many others have said, he only gets rough on people he knows and who should really have known better. And as a project lead myself (tiny team, tiny project compared to the Linux kernel), what about the lead's stress? I've had to deal with users being profoundly (let's be kind) dense and completely unable to focus on the most in-your-face things but I take a few deep breaths and calm down before I reply because they're users, they don't/shouldn't know better, it's not their job and it's their first time using my system. But if a long-time contributor who should really have known better pushed code that broke something, then that dude's gonna have it. And, do keep in mind, we've seen some mild and public outbursts from the guy who is managing this huge freaking project, compared to what goes on in private on similarly sized organizations, I'm willing to bet that Linux will come off as the mild mannered one.
None of this matters though since the Linux kernel is flourishing, there simply isn't a problem to fix.