ESR's email conveys strong negative feedback—as Linus needed—and in the most deeply respectful and complimentary way I've ever seen in an "email rant". Especially from ESR lol. It's very clear that he means it from a heartfelt place and intends it to be productive.
If you read that email and feel snark from it, that's projection on your part, and it speaks to an uncomfortability with criticism in your world view. You might find life happier if you see that people give negative feedback not to shit on you or snark, but because they care and want to see you succeed.