I'm guessing it is easier to get through the interview when you are simply connecting in Amsterdam, rather than originating there. Also, since Umar Farouk Abdul Mutallab was connecting from a flight from Nigeria, his home country, the only questions he may have been asked would be about the purpose of his trip to America. I assume if was asked, his answers were convincing.
No doubt Al Qaeda trained him for this.
The passenger who witnessed that he had no passport, sent a copy of his ticket receipt for proof he observed the terrorist before boarding. In his statement he adamantly stated the supervisor said” we let people on all the time from Nigeria without passports, due to the fact of problems with that country.” This must be a known fact to the terrorists.
Also, I have since heard a few reporters/radio personalities state Denmark has its reputation for laxity.
That if he was cleared in one country he would not be questioned in another.
All of it makes about as much sense as Napalitano