I've been told that I shouldn't work for a competing magazine even though I'm not a full time employee, have no benefits of any kind, and I'm certainly not being paid a retainer. Being pseudonymous solves that problem.
Anonymity isn't the same as writing pseudonymously. The point here is that the writer was posting anonymously - the pseudonym was just a cover.
Potentially he was posting anonymously in the public interest as a whistleblower, which is one angle that could have been made more of.
If people are forced to give up anonymity online, blogging gets much less interesting. And much less useful.
There's a series of anonymously-written books in the UK about a woman who works as a call girl. If that person was named, it would very likely damage the earning potential of those books.
Why should a journalist have the right to destroy someone's livelihood for the sake of a story?