Its their thing among the Arab population. I personally don't particularly disagree with the FBI on this one since they are acting against groups which have been acting aggressively against not just the US government but individual people for a very very long time.
I think the feds have some sort of handle on a number of social networking sites used by the Arabs, so they get their hooks in one that is known anyway, set up and bust them, then the publicity of the bust gets them all to distrust various Jihadi contacts from the US.
The real quality takedown however would be in dealing with Saudi diplomats or relatively high placed representatives of a leading Muslim outfit that is doing the "cash for newsworthy events" thing that a lot of the Iranians and Syrians have been pretty well known for in the Middle East, and Khaddaffi had tried less than entirely successfully with some Muslim themed street gangs out of Chicago. They had some success until they ran into a rivalry with some more established Black Muslim groups.
So a lot of questions remain on whether or not actual foreign intelligence operatives have ever been caught attempting to pay for terrorist acts. The closest thing I have seen was a series of busts of intermediaries in the arms trade, however back around 2004 or 2005 a major police equipment supplier (Galls) got raided for selling a bunch of night vision equipment to the Iranian national police.
Someone associated with this site actually was involved in that case a little bit but the government would never officially acknowledge his help since that individual later came under investigation on another case. In each of the major investigations involving allegations of international smuggling, it was people far closer to the government who were actually providing hardware to the bad guys, although we have not gotten any heat since the BATF has been embroiled in the Fast and Furious scandal after burning a couple of our people and refusing to make any equitable deals.
I have been really curious as to why there have been no public busts of some sheik or representatives of some sheik's out of say, Oman or Yemen who were offering money for terrorist acts. You could fake up some attacks under controlled circumstances, publicize it, then when their foreign ministries and various agents step up to reward the perps, you gain intel, pull off a couple more fake terror attacks, then bust the lot of them. No so much false flag stuff with a real bodycount, but something totally Hollywood. The ruse would only have to last for a few months. Crash an empty cargo plane in the desert, claim it was a successful terror attack, get paid, then find out everything about the terrorist paymasters.