It was massively upvoted because many, many people agree with a lot of the content of the article. If this was lesswrong or reddit, the post might have a negative score, it would certainly be controversial.
Personally attacking the author is okay because
(a) He's not remotely as active, committed or useful a commenter as Patrick.
(b) Obvious self-promotion is taboo among technical people and among their broader cultural peers, nerds, geeks, whatever. Demonstration of talent in the course of something else is the way to go. lsc has some great comments on this, and makes the point that business people are just not like this, at all. Sebastian is much, much more like them in this regard than Patrick.
But many people probably agree with him among the lurkers because not all of his comments on this thread are negative, they're hovering around 1 or 2.
Now personally I too think this was inappropriate, but if he had run it by Patrick, it'd have been fine. It's not like I, and the no doubt many other, habitual patio11 comment stalkers, couldn't have writted this or something like it<1>.
That said, this post probably wrecked Patrick's day. I felt uncomfortable reading it and I'm way less territorial or private than normal. It will probably occasion an Xing of his consulting rate though, which will leave Patrick more time for leisure or working on his own stuff, so distasteful as even I find it, it may in the long run turn out to be a _small_ favour. Maybe it accelerated his consulting trajectory a year. Whether that's worth what was no doubt a punch to the gut I don't know.
<1> also yummyfajitas, lsc, pg, tpatecek, tokenadult, cperciva, RiderOfGiraffes, ErrantX, btilly, moultano and nostrademons