I work among military pilots. They all agree. There's plenty of information available that can be used to learn how to fly an airliner. MS Flightsim is certainly a robust simulator with enough detail to learn the basics.
The easy part is flying. The hardest parts are landing and take off.
With regard to navigation, the article neglects to mention GPS. Many general aviation pilots use handheld GPS receivers for navigation and there's no reason to think the terrorists wouldn't spend $200 on a receiver as well.
