April – I don’t really see any problem with the blog post you provided a link to. In fact, as the agent points out, I can never believe the number of would-be writers who rant and rave in their blogs and other public forums about the incompetencies of particular agents, publishers, editors, etc. It ain’t exactly the way to win them over as friends, and it reflects very poorly on a writer’s professionalism. I know of one would-be writer who constantly berates agents by name, and then complains that he can’t get an agent to represent him — go figure.
I also think the agent who wrote the blog you linked to makes another often under-appreciated point: namely that publishers (and agents) want to “discover” a writer who is new, and fresh, and who hasn’t posted the best work they have to sell on their own blogs. That doesn’t mean you shouldn’t post good samples of your writing – you definitely should – but you shouldn’t post any significant portions of any works you’re hoping to someday sell. I also think it’s fine to post personal stuff, IF you make it interesting by virtue of excellent writing.