I think, this is in part a consequence of the deification of Steve Jobs, who might have adopted a similar stance towards his partners/employees. Such behavior is now automatically assumed to be acceptable by some subset of people. The No Asshole principle is passé. The author may have written such an email irrespective of Steve Jobs influence. But the audacity to post it on his own blog for everyone to "admire" certainly has to do with the publicity around the Jobs' supposed douchiness.