I think it's possible to blend a polite environment and a no-nonsense environment as long as you're physically working together, or at a minimum doing video conferences. IIRC, Linus said that one of the reasons he used such strong language and is so abrasive on the mailing list is because so many communication cues are lost when you don't have tone of voice and body language to add context to the actual words. Being over the top aggressive and harsh was his way of ensuring that his message was completely unambiguos. That said, most people don't want to work with someone like that, and he addresses this when he talks about people leaving kernel development specifically because of him. If they continue using the mailing list for development, I think we need to expect that development will slow a little at first since there will probably be more back-and-forth between developers. That said, hopefully having a better working environment will encourage more people to be kernel developers, negating the slowdown caused by a more cordial mailing list. I'm also really happy to see Linus setting a positive example for taking care of yourself in addition to your project.

I don't see why you'd ever need to go further than "I strongly believe that your view is incorrect, and here is why". Attacking people is not "calling bullshit"

In my experience saying the words "your view" often makes it personal for the other person, which can lead to them defending that view much stronger than if the criticism goes towards "this view", which invites objectivity.

Probably not a huge game changer, but it's definitely a little hack that I think has served me well over the years.