Yes, they frequently engaged in unsavory criminal activity, but let me tell you, any terrorist trying to smuggle in a dirty nuke or something would end up under the dock with a meat hook sticking out of his head.
I'm sure we're all nostalgic for the days of organized crime, but I can guarantee you that organized crime has been only too happy to assist terrorist whenever it was financially advantageous to do so. The mafia is not patriotic.