Treat your volunteers well, or why should they continue volunteering?
Kernel maintainers have plenty of other opportunities.
I don't know if they are volunteering or being paid. The other person said they are being paid.
Either way, no one deserves being talked down to like that, even if they made a mistake. It's a matter of respect and self-respect. And as a skilled person like a kernel developer, it should be trivially easy to find other work in a more appropriate environment.
That being said, maybe I'm missing something. Torvalds has been known to be like that for a long time (although that seems to be over now). And still, Linux has been developed over decades. So apparently, skilled people flocked around Torvalds, or maybe rather his project. Not entirely sure why, but I'm taking it as a hint I might be missing something.