The school administrator who arranged for a taxi to take Umar back to the airport told reporters the taxi was the end of their responsibility for the Nigerian who came to Yemen to learn Arabic. To learn Arabic? Of course in hindsight that might have raised some flags but we can't investigate everyone who wants to learn a language heavily reliant on the sounds of phlegm lodged in the back of the throat.
Updating my original post with this new information has further solidified my resolve (from 2001) that we cannot rely on anyone else in the world to look after our interests of national security. Yemen should be punished for allowing this terrorist to leave their country, either by their own negligence or for aiding Umar Farouk Abdulmutallab. Uh oh, did I just start a conspiracy theory? *Cue intense music.