I’m not sure what point you’re trying to make with the quote, but I’ll say it’s a good quote and I agree with it. If we apply it to this example, I would say that ol’ Dr. Dao should never have been manhandled the way he was, regardless of his refusal to leave (which was in within his contractual rights, from what I understand). The idea that an airline would have a paying passenger violently removed simply to make room, or that the security guys would resort such aggressive tactics, is an indication that these people and organizations do not hold to those old standards of behavior. Forcing a seated passenger to leave at the literal last minute is a huge imposition, and the airline, if they had any decency, would have recognized that and acted accordingly. Instead, they thought they were in their legal right to boot the poor fellow off the plane in an undignified manner, and so they did, decorum and decency be damned.
It may be his right to stay in his seat; but, if the owner says go, he should go - because the law can't provide a peaceful solution to all situations.