It may be a counterpoint, but it is also one of the milder rants from Linux: No expletives; no colourful descriptions.
Yes, it's critical, but is the criticism unwarranted? He is questioning why one of the most senior maintainers is directly contradicting one of the most central "edicts" from Linus on the kernel development: Don't break user-land. In the message, Linus directly quotes Alan as arguing that breaking userland is ok.
Of course Alan was/is free to disagree, but he should have known very well that Linus would never let that fly. Not least because Linus had told him it wouldn't, and he kept pressing for it.
What was the alternative? From the outside, it looks like Alan repeatedly avoided doing what Linus told him needed doing. Linus could not have backed off without sacrificing the guarantee of not breaking userland.
If you read the whole thread Linus was wrong. He was constantly confusing two different bugs (despite Alan pointing this out to him multiple times), and the fixes he was yelling at Alan for not applying would have caused other things to break.
Ooof. If I'm reading that thread correctly, Linus wanted to leave in a bug that would probably allow a local attacker (or maybe even a remote attacker) to execute arbitrary code in the kernel, just to avoid the risk of breaking userland code that did questionable thing that happened to work before by fixing it.
So reading this thread, I keep asking "could Linus have said what he needed to say in nicer terms and gotten better results?" I think so. In every Linus rant I encounter he goes on and on about the problem, then the person causing the problem, and typically attacks the developer. It's one thing to rule with an iron fist, it's another to target individuals and not the behavior.