They knew their names already, Tom.
The FBI knew their flippin' names. The FBI had pictures. What the FBI didn't have was a conversation with anybody about it, and it wasn't because they needed permission to eavesdrop on people without warrants. They had information already, gathered the old-fashioned un-Patriot way. It's because there was no conversation.
Why was there no conversation? I don't know. But it's not outside the range of my imagination to think that part of it had to do with the boss's friends. They were looking for a particular type of conversation, and it wasn't supposed to be about Saudis. It was supposed to be about Iraqis.