It was the covering up of what his advisors did that got him into trouble. I agree with you. Had Nixon stood back, took some heat but not covered up for Dean, Colson, and the others and the others, then he would have survived.
Of they could have tried to say Nixon planned the whole thing but the evidence shows he had no knowledge of the issue until the story broke and arrests were made. The Dems would have done the guilt by association smear and demanded a resignation but Nixon at that point would have had grounds to “stand pat”...and call their bluff. The cover up took away that option.