And since the pilot saw it he already radioed ahead and the entire crew and the passengers would have been sequestered immediately upon landing for questioning.
Again, the pilot might have seen something- a trail of smoke, a bright light and not known or suspected what it was until- he was interviewed by the FBI.
"the entire crew and the passengers would have been sequestered immediately"
Do you think their families may wonder where their loved ones are? Or where they sequestered as well? Plus if everyone was sequestered, then how did this one report leak out? And if one got out, I would think many more would as well.
Bottom line, I have no idea, but I still find this hard to believe.