He lost money on his book, meanwhile, Python 3 usage rose during that same period and it's still on the rise, so I would imagine (hope) he's just referring to personal commercial disaster. http://dev.pocoo.org/~gbrandl/py3pkgs.png shows a pretty consistent increase in packages (keep in mind many are still mis-classified as 2.x only), and although I don't have stats to back it up, the number Python 3 related posts on Reddit, comp.lang.python, and SO seem to have risen as well.

All I took away from his comment was that you don't always win being an early adopter, especially when it comes to writing books. Maybe that month was an anomaly? Python 3 adoption is right where we expected it to be, and with projects like NumPy/SciPy recently adding 3.x support, the floodgates are open.