Could he have meant that Zell "learned at Maddox's knee," so to speak?
Nope. It was a smear. The one thing Lester Maddox is remembered for is being a segregationist. Maddox owned a restaurant in Georgia, and he refused to serve black people. He ended up closing his restaurant rather than integrate, and he became governor because of that notoriety. Since Miller was around before Maddox was, there was no way Miller learned at Maddox's knee. What Gergen did was a blatant, race-baiting, smear.