I think the original point being made was that having such extensive airline industry experience actually makes you unqualified to lead the FAA. For instance, Dickson, through his position at Delta, has likely developed strong ties to counterparts at Boeing. This made him unable to adequately address the safety issues of the 737 MAX.

My follow-up point was that experience in regulating airlines is more important than experience running an airline when it comes to leading the FAA. However, those who regulate airlines as a career are unlikely to be big political donors, so they're unlikely to be chosen to lead the FAA.