An article from the former airline pilot explaining airline unions:
Philip Greenspun is tech entrepreneur that flies as a hobby. He flew in an airline for a short while, but he is not a "former airline pilot".
Sully, on the other hand, writes in his book:
> “I also understood the history behind our profession’s dependence on a seniority system. It started in the 1930s, as a way to avoid the favoritism, cronyism, and nepotism rampant in the early days. It was about safety as much as fairness. It insulated us from office politics and threats to hinder our careers if we didn’t “play the game.” A layman might think such a seniority system would lead to mediocrity. Nothing could be further from the truth. Pilots are a pretty proud bunch and they find it rewarding when they have the respect of their peers. The system works.”
The seniority system is what gives the captain the power to say no to the airline when pressured to fly in unsafe conditions without repercussions.
Philip Greenspun could just say no and go back to his life as a retired tech millionaire.
"He flew in an airline for a short while" literally means that he is a former airline pilot, i.e. in the past he piloted aircraft, while being employed by an airline. Currently he also works as a helicopter instructor.
He was not subject to the same constraints and incentives that professional airline pilots are subject to.
For example, without a union and the seniority system, airline pilots that are pressured to fly with badly maintained planes are faced with a major dilemma. They can agree and risk their passengers, or refuse and face repercussions. Their livelihood and social status depends on them keeping their jobs, and the vast majority don't have the resources to withstand lawsuits.
Philip Greenspun can just go back to fly his collection of private planes and helicopters. He faces no repercussions if he refuses or goes to the press.
He has no skin in this game.
He just doesn't have the insider's perspective.
He can disagree with Sully's reasons why the seniority system is important for safety, but he should at least address it.
Moreover, Sully, as senior pilot, was direct benefactor of the union system that exploits younger pilots, so his opinions should be scrutinized first of all.