McCain's friendship with Keating died sometime prior to the scandal hitting the fan, because unlike Cranston for example, he refused to be the guy's totally amoral errand boy for cash. That is one reason why McCain received only superficial wounds from the affair. Isn't there enough to bash McCain over without stooping into something not all that far from the sewer? But his behavior with Keating has been repeated by him over and over again - plausable deniability while associating with sleazebags and and accepting handouts.
The guy is a slimy little weasel