The evidence does not support the contention that Nixon was involved.
The "smoking gun" tape revealed that Nixon was told about it two weeks before he said he knew it. During that two week period he was technically guilty of obstruction of justice for not coming forward with the information.
I have never been an admirer of Nixon, but I am convinced the media had an all-consuming hatred of Nixon because he brought down Alger Hiss. During 1973 they kept up a steady drumbeat of criticism and condemnation until even the Republicans caved and asked him to resign.
By the way, when the KGB files were finally opened in the mid-'90s they showed Hiss to have been on their spy payroll, along with that other great liberal icon I.F. Stone. Haven't seen this covered in the MSM have you?