Sarah Sharp is a member of a very rare group. She's a Linux kernel hacker. Even among that group, she's unique - not because of her gender (though that probably is distinctive in many of the group's social gatherings), but because she's brave enough to demand civil behavior from the leaders of the community. I applaud her for that.
Now, I have immense respect for Linus Torvalds and his crew. I've been a direct beneficiary of Linux in both professional and personal contexts for soon to be two decades. The skills this group demonstrate are possibly only matched by the level of quality they demand from each other. However, unfortunately that bar is often demonstrated only on the technical level, while the tone of discussion, both in-person and on the mailing lists, can turn quite hostile at times. It's been documented many times, and I can bring no value to rehashing that.
However, I wanted share some experience from my own career as a developer, manager of developers, and someone who has been both described as demanding and who has needed to report to others under very demanding circumstances. I've made some of these mistakes myself, and hope to have learned from them.
Perhaps not so surprisingly, the same people in the community who defend hostile behavior also, almost by rule, misunderstand what it means to behave professionally. There's a huge difference between behaving as in a workplace where people are getting paid, and behaving professionally. The latter is about promoting behaviors which lead to results. If being a asshole was effective, I'd have no problem with it. But it's not.
To consistently deliver results, we need to be very demanding to ourselves and to others. Being an uncompromising bastard with regards to the results will always beat accepting inferior results, when we measure technical progress on the long run -- though sometimes experience tells us a compromise truly is "good enough".
However, that should never be confused with being a bastard in general. Much can (and should) be said about how being nice to others means we're all that much happier, but I have something else to offer. Quite simply: people don't like to be called idiots and having personal insults hurled at them. They don't respond well to those circumstances. Would you like it yourself? No? Don't expect anyone else to, either. It's not productive. It will not ensure delivering better results in the future.
Timely, frequent and demanding feedback is extremely valuable to results, to the development of an organization, and to the personal development of the individuals. But there are different types of communication, and not all of it is feedback. Demanding better results isn't feedback, it's setting and communicating objectives. Commenting on people's personalities, appearance, or otherwise, let alone demanding them to change themselves as a person isn't feedback nor reasonable. Feedback is about observing behavior and demanding changes in the behavior, because behavior leads to results. Every manager has to do it, never mind whether they're managing a salaried or voluntary team.
However, calling people names is bullying. Under all circumstances. While it can appear to produce results (such as, making someone withdraw from an interaction, thus "no longer exhibiting an undesirable behavior"), those results are temporary and come with costs that far outweigh the benefits. It drives away people who could have been valuable contributors. What's not productive isn't professional. Again - I'm not discussing here how to be a nicer person, but how to improve results. If hostility helped, I'd advocate for it, despite it not being nice.
The same argument can be said about using hostile language even when it's not directed at people, but to results. Some people are more sensitive than others, and if by not offending someone's sensibilities you get better overall results, it's worth changing that behavior. However, unlike "do not insult people", use of swearwords toward something else than people is a cultural issue. Some groups are fine with it, or indeed enjoy an occasional chance to hurl insults at inanimate objects or pieces of code. I'm fine with that. But nobody likes to be called ugly or stupid.
In the context of Linux kernel, does this matter? After all, it seems to have worked fine for 20 years, and has produced something the world relies on. Well, I ask you this: is it better to have people selected (or have the select themselves to) for Linux development by their technical skills and capability to work in organized fashion, or by those things PLUS an incredibly thick skin and capacity to take insults hurled at them without being intimidated? The team currently developing the system is of the latter kind. Would they be able to produce something even better, if that last requirement wasn't needed? Does that help the group become better? I would say hostility IS hurting the group.
Plus, it's setting a very visible, very bad precedent for all other open source teams, too. I've seen other projects wither and die because they've copied the "hostility is ok, it works for Linux" mentality, but losing out on the skills part of the equation. They didn't have to end that way, and it's a loss.