True, but OTOH this woman is such a babbler, on so many websites, I think Al Qaeda would've found her a security risk to their operations.
But she's perfect for them if they want to do a test-run. In this case they might have been testing to see if someone passing through LHR from somewhere outside the new security zone could board a flight for the US without the additional screening.
For such a test, you wouldn't want to use any real soon-to-be or might-be terrorist; you'd want to use someone who could claim they were doing it as a stunt to prove how inept the process was. Mayo would seem to be perfect for that; as a rabidly anti-American journalist she could be counted upon to do what they asked because they could sell it to her as a great story.
What happened to her after she got on the plane for DCA was irrelevant to them.