Not that I disagree with the general point, ivy- but isn't using FBI agents quotes particularly weak evidence? I mean these guys livelihood depends on strong and viable mob. If the mob is weak or just running video poker- that means no FBI mafia squads, no convictions, and therefore no outrageous government funding and no more gigs.
As sinclair put it "“It is difficult to get a man to understand something, when his salary depends on his not understanding it"
No, because even without a viable LCN family in their jurisdiction, any FBI office has plenty of other things to deal with. They have no need to make up threats that aren't there. Which is why they recognize 10 remaining families at most now, rather than two dozen or so.