Funny link, but not quite accurate. ESR has plenty of street cred. He has been active in the hacker community for over 30 years, and his work on LISP and Emacs is more than enough to place him in the annals of computer history. Additionally, I think that his essay "The Cathedral & the Bazaar" is the basis for how Linux and most other open source projects are run today, and his exposure of the potential flaws of Brooks' Law is probably exactly what got many companies, small and F500 large, to use Linux.
For more info, read Brooks' "The Mythical Man-Month" - clearly, your buddy has not done so, and therefore is unable to understand "The Cathedral & the Bazaar", which is probably why he doesn't like it.