Alright. I've read the above, and I can come up with four possible conclusions:
1: it's exactly as the article says, they are probing for the real thing.
2: It's a resource diversion exercise. (more later)
3: They are doing it to give everyone the heeby-jeebies
4: It's complete bull.
1: if they are doing the real thing this way, they don't have a chance of success. alright, pre-911, if an Arab came to a flight school and asked to learn how to fly, then only took an interest in turns, you'd find him weird, but you wouldn't think of him as a terrorist. Nowadays, dry runs like these would just prick everyone's ears up, and that's not what they'd want.
2: More likely, if they are terrorist linked, they want the security to be tightened up and resources diverted as their "attack", inconveniencing the great yankee pig-dogs by making them jumpy.
3: they could be just a bunch of students/bums/whatever, who hate America and think it's a great joke to scare those christian/white/western/american/whatever infidel by pretending to be sinister terrorists.
4: Someone doesn't like Arabs.
I don't think it's 1, 2 sounds as bad as it gets but is not beyond the realms of possibility, however I'd put money on either 3 or 4, depending on the author's track record.