Wiki says JMS worked as a journalist himself in addition to his other jobs (150 articles), which makes it even odder.

Not necessarily - he'll also have known a lot of inside dirt.

I know people who deal with sensitve issues, and all of them have had bad experiences with the media.

I think part of what jms is doing is not slagging off journalists as such, but highlighting the power of the media. And unfortunately nobody ever notices that when (if?) it is used to do good.