[bryanlarsen]

The FAA needs to know that if the same failure would have happened at a different point in the sequence, that all human lives would be safe.

So if Scott Manley was right and it was a landing leg strut failure, SpaceX could quickly report that and close the investigation. A landing leg strut failure would never threaten human lives so that's all the FCC cares about.

OTOH, if it was an engine failure leading to the rocket coming in hot (like others have speculated), it's possible that the same problem at a different point in the flight path could threaten lives. But SpaceX has redundancy in basically all systems for the "going up" portion of the flight so it could just say "yup, if that had happened at a different time the redundant systems would have had to take over".

During landing the center engine is a single point of failure. Going up they have 8 other engines and can get to space on just 8.