[Ditto]

I came to believe beyond any reasonable doubt that Nixon did not lie or direct a cover-up, and that if he had gone to trial in the Senate, he would have survived.

I doubt he would have survived a trial. The Senate was totally controlled by the Democrats then (60+ seats?) They would have arm twisted enough votes to convict regardless of the evidence.

And if he had survived trial, he would have still been completely neutered. Resigning was the only real option left to him. The Pardon may have been unnecessary, however. A trial in court may have vindicated him in the public eye.