Well, it's nice that Popular Mechanics gave enough credence to the conspiracy wackos to "conduct an independent investigation" of the theories. And, they managed to snag one of the all-time time wackos of our time, John McCain to write the forward. Wowsers.
People can and will believe whatever they want. On 9/11, I saw video footage of two commecial jets slamming into the two tallest skyscrapers in New York City; I saw huge fireballs erupting from those crashes; and, I saw that after burning furiously for approximately an hour and one-half, the supporting structural members were no longer able to support the weight of the remaining structure and collapsed. There's nothing suspicious about it; it is explained in the theories of physics and it has been better explained by others not trying to sell a book.
I think they will try to resolve the issues relating to the fall of WTC 7 and using cell phones at 25,000 feet.