People seem to be forgetting here that the problem wasn't that a mistake was made. We all make mistakes, and in fact the -rc series is part of the testing process; the mistake was caught before we cut the final release, so the development process worked.
The problem was rather the attempted justification of the mistake by claiming that perhaps it was the userspace program's fault. That was what set off Linus, and caused him to yell at Mauro. (It would be like someone trying to claim that perhaps the victim of sexual harassment was at fault. Sometimes, when someone blames the victim, the best response is a rather public chewing out of the person who tries to deflect blame from themselves and onto the victim.)
This is not a new message. Mauro knew this already. He just didn't internalize it. Sometimes, after saying the same thing quietly, and being ignored, you have to raise your voice in the hopes people will listen. Ultimately, of course, if people continue to refuse to listen, all you can do is fire them (which in the open source world, is to publically tell them not to bother to send you pull requests). Short of taking that drastic step, it's not like an open source maintainer can dock someone's pay.
In general, Linus only yells at people who should have known better. Mauro definitely fell into this camp.
The problem was rather the attempted justification of the mistake by claiming that perhaps it was the userspace program's fault. That was what set off Linus, and caused him to yell at Mauro. (It would be like someone trying to claim that perhaps the victim of sexual harassment was at fault. Sometimes, when someone blames the victim, the best response is a rather public chewing out of the person who tries to deflect blame from themselves and onto the victim.)