That's how it works. Buying a mass of fertilizer is not as obscure a manner of waging terror as say only practicing takeoffs in an environment that had never witnessed such mental illness before.
As for some Muslims looking like westerners, my bet is our border control is fairly well trained in "profiling", and connecting dots of potential hotspots that could provide camouflage for the idiot delivery system (the demented terrorista).
Not every asshole will be caught unfortunately, but profiling will help catch many. It's when political correctness enters the equation that people get killed, and that after ample warning bells have been set off... as what happened at Ft. Hood. They knew the guy was a brick short of a full load, yet they closed their eyes because of PC.
Who is to say the terrorista's won't use this precise cover because some think they are harmless folk. Sorry, but Muslims have been responsible for these dastardly attacks around the world and none should be sloughed off as harmless. If they want to expunge the profiling, then these people should turn on the idiots and aggressively and constantly denounce them... but that hasn't happened.
Instead, cartoons, cartoonists and film makers are protested and killed.
Let's say they have their priorities a little farked up.