Welcome to the new era of "fake regulators".
If the FAA behavior in this matter at all surprises you, check out the launch of the MD DC-10 back in the early 1970s. Here's the short version.
1972, AA flight 96: rear cargo door blows out, collapsing the rear cabin floor and severing some control cables to the rear control surfaces. The pilots have enough control and expertise to get the plane landed.
NTSB: There are severe design flaws in the DC-10's cargo doors and cabin floor that need to be fixed.
FAA: We'll let MD handle the problem as they see fit; there is no need to issue an airworthiness directive to force proper repairs.
1974, TA flight 981: rear cargo do blows out. This time the floor collapse is more catastrophic, severing all controls (hydraulic and cables) to the rear control surfaces. The plane is uncontrollable and crashes, killing all 346 aboard.
House of Representatives investigates the cargo door problem, and an airworthiness directive is finally issued to force proper repairs. It seems that MD, left on their own, came up with lousy, ineffective solution, and then didn't properly implement (including training the airlines how to "properly close" doors) the lousy solution they came up with. Also, it seems that the cargo door issue was known by MD and its subcontractors during the design of the DC-10.