I think whoever recieved this would be completely fine to report Linus to HR or something. The fact somebody thought to circulate it is suggestive that it crossed a line. I do appreciate he does seem to really care about the kernel. He could maybe tone down the hysterics a little.

I think if there's a lesson here its "Never hit send while you're angry" always wait until your hormones to subside before sending an email because emails are records and people don't have good judgement while angry, so an email sent in anger is just a record of your poor judgement.