I understand that very well, but it doesn't mean that those guys were terrorists on a dry run or anything like that at all.
And the no reason to detain them did not include their lack of visas as it seems their's were all expired...
This caviler attitude is why America is such a ripe target. Syria is at war with us and is sending troops into Iraq to kill our men. Why are they also sending Koran singers to play music in casino's? Does it not seem just a little strange to you? That is like a Vice Cop that works as a hooker on the side.
Clue, get one before it gets you.