I see you really don’t know very much about politics and recent American history.
I challenge you to find the quote, “Let so-and-so be so-and-so” prior to Michael Deaver saying “Let Reagan be Reagan” in connection to Deaver’s public relations strategy for the Reagan White House. You won’t find it, because Deaver coined the phrase.
Reagan, of course, would never have been so arrogant as to use the phrase on himself, unlike Herman Cain’s no-name staffer, who clearly exhibits a surfeit of arrogance and stupidity both in the dumb commercial he starred in, and in everything he has said subsequently.
He should be fired immediately, and every day Cain fails to fire him shows a lack of judgment on Cain’s part.
You are failing to understand how language works. Even if no one ever used the phrase prior to Deaver, that was thirty years ago. What matters today is how the expression is used today.