The point of this study is to supplament previous studies of ball lightning. The most widely accepted theory is that ball lightning is a ball of silicon gas, resulting from lightning striking the ground. That obviously didn't address the cases of ball lightning appearing in and around aircraft, which is the gap this study fills in.
So now it seems we have one workable theory of ball lightning. To claim it is incomplete, you need to find cases of ball lightning that were both a significant distance away from the ground AND far, far away from any windows.
My doubts about this theory lie in the various behaviors when ball lightning encouters solid objects... Sometimes it burns a hole, while other times witnesses claim it passed right through solid objects without causing any damage. That seems to indicate there may be two very different types of ball lightning, but perhaps the ground versus windows source will prove to generate a sufficiently different type of ball which will suit both observations.