Even so, mergers foreclose options to promote competitiveness. For example: no well-capitalized companies from outside the immediate industry could buy MDD to enter the space (as RocketLab bought Iridium). A failing MDD could have limped along for a decade or more until a tech billionaire (say) decided to buy in and reinvigorate it. It could have been split up, allowing smaller entrants to buy parts of it. It could have been allowed to fail, so any of these types of transactions could have happened at smaller dollar amounts.
Basically, allowing it to merge with its largest competitor was the worst possible outcome for competitiveness and long-term health of the industry.
More to my point, though. There's no real reason our existing anticompetition laws should not have been enforced here. Our culture of selective enforcement of laws is a cancer that manifests in all kinds of negative ways. I strongly advocate that we move towards being a society governed by written laws.
That unlikely hypothetical scenario makes no sense. MDD was going to drop out of the airliner market no matter what. They simply weren't viable. If they hadn't merged with Boeing then it would have been with some other large aerospace or defense company like Raytheon or Lockheed Martin — possibly after a trip through bankruptcy. No "white knight" billionaire was ever going to save them.