Neither you nor I know what caused Cochran to say it, but I have a good guess: McCain yelled at Cochran at some point and Cochran took offense, and now he’s exacting his revenge. Hardly proof of insanity.
And I guess the words that he yelled are having consequences. Words have consequences.
Why do you think it will hurt McCain? Shouldn't it help him? He didn't get where he is today by playing nice with conservatives. If Reid was complaining that McCain yelled at liberals instead of conservatives, would that hurt McCain or help him?