Not trying to do a 411A or a Guv here, but the statement that "board member George Black said he was unaware that any civilian aircraft had ever lost a vertical tail fin to wake turbulence" is completely untrue.
In the early or mid - 70's, a BOAC 707 lost it's vertical stab in an encounter with a rotor off Mount Fuji, Japan. It led to the inflight breakup of the machine, with the loss of all on board.
There are photos (somewhat grainy, but horrifying, nonetheless) in several publications of the machine during it's encounter and the subsequent breakup.