The meeting that led to the investigation took place in April, 1987, a few months after McCain was elected to his first Senate term. He had a personal (and politically questionable) relationship with Keating prior to that, but that had more to do with campaign contributions, Cindy McCain and her father investing in a Keating shopping mall, and some trips the McCains took on Keating's dime (repaid later, mainly because of the potential political fallout).
The Senate Ethics Committee did not claim it didn't have juridiction:
Based on the evidence available to it, the committee has given consideration to Senator McCain's actions on behalf of Lincoln Savings and Loan Association. The committee concludes that Senator McCain's actions were not improper nor attended with gross negligence and did not reach the level of requiring institutional action against him. The committee finds that Senator McCain took no further action after the April 9, 1987, meeting when he learned of the criminal referral. . . .
Senator McCain has violated no law of the United States or specific Rule of the United States Senate; therefore, the committee concludes that no further action is warranted with respect to Senator McCain on the matters investigated during the preliminary inquiry.
Quoted in the New York Times here. (http://www.nytimes.com/1991/02/28/us/excerpts-of-statement-by-senate-ethics-panel.html?pagewanted=3)
I remember what the Arizona newspapers (and the letters to their editors) were saying about McCain and his opponents at the time. He was re-elected largely because the majority (about 55% at the time) of the state's population wanted to make sure that the Democrat didn't get the seat. He did benefit from five years' separation from the event, but not quite as much as you think. He wasn't well-liked here for more than a dozen years after he moved here, and there is still a significant portion of the conservative community in Maricopa County that thinks he's too liberal.
Re: McCain and the Keating Five
The Senate Ethics Committee did not claim it didn't have juridiction:
Based on the evidence available to it, the committee has given consideration to Senator McCain's actions on behalf of Lincoln Savings and Loan Association. The committee concludes that Senator McCain's actions were not improper nor attended with gross negligence and did not reach the level of requiring institutional action against him. The committee finds that Senator McCain took no further action after the April 9, 1987, meeting when he learned of the criminal referral. . . .
Senator McCain has violated no law of the United States or specific Rule of the United States Senate; therefore, the committee concludes that no further action is warranted with respect to Senator McCain on the matters investigated during the preliminary inquiry.
Quoted in the New York Times here. (http://www.nytimes.com/1991/02/28/us/excerpts-of-statement-by-senate-ethics-panel.html?pagewanted=3)
I remember what the Arizona newspapers (and the letters to their editors) were saying about McCain and his opponents at the time. He was re-elected largely because the majority (about 55% at the time) of the state's population wanted to make sure that the Democrat didn't get the seat. He did benefit from five years' separation from the event, but not quite as much as you think. He wasn't well-liked here for more than a dozen years after he moved here, and there is still a significant portion of the conservative community in Maricopa County that thinks he's too liberal.