How could they have not heard the rumors everyone else did and not ask tough questions?
This is what happens to any business that trusts their president without question and has no oversight.
The board is either incompetent, blind, or complicate.
Likely the board had no alternative but to continue trusting without actual evidence....and obviously if Falwell was questioned he continued to cover, I believe for 'fear' of what he defiantly knew would be the fallout on is family, his position and the University and it's affiliates.....as well as over time the election.
The idea that extortion was also in play only added to the affair and the desperation to conceal this from all that we see now happening
Time was the ONLY thing that could be obtained before this was to explode.