This has been exercised to the Nth degree on PPRuNe. All the arguments are known but none of us have the knowledge that the Captain and crew had, nor have the technical reports that showed what really happened.
At the risk of starting the whole thing again, I reckon the FAA have had some American carriers whispering in their ear. I would take BA on any day of the year under (just about!) any circumstances. But there is political mileage to be made out of this. If that means more people being delayed for no purpose, then so be it.
I sit to be corrected.