Mayor is an awkward role to grow out of. Lindsay retreated to a law firm. Dinkins ended up playing tennis and making goodwill appearances. (Abe Beame got lost in the shuffle, but that was perhaps inevitable.) Instead of going gently, however, Ed Koch went around the bend. Sure, The People’s Court was an inspired move. But his latest incarnation – finger-waving conscience-for-hire – is as ill-suited to this highly partisan, highly culpable, and, yes, highly lovable crank as the desired role of diplomat-in-chief is for Gracie Mansion’s current occupant. In Al D’Amato’s new campaign ads, Koch presents himself as a nonideological arbiter of taste and restraint – à la Martha Stewart. “You’ve crossed over the line,” he chastises Chuck Schumer, “and it’s inexcusable.” Kinda makes you wish he’d ask us how he’s doing just one last time.