I don't think he needs to be. It's just a standard tactic at their blog. They always come off as being a bit contrarian for the sake of it. Or they just want more traffic.

While talking to Jason Fried after Startup School 2009, I realized that trolling on their blog is what they do instead of adding features to their products.

Everybody needs a creative outlet! Letting everyone at 37signals post directly to SvN is a way to keep the minimalists sane.