For Michael Gerson there is one simple explanation for Objectivism: adolescence.
Many of us experienced a few unfortunate years of invincible self-involvement, testing moral boundaries and prone to stormy egotism and hero worship.
Michael obviously seems to know what he is talking about. Either himself or many of his friends and family must have been egotistic, self-involved and immoral hero worshippers during their youth. So basically what we are dealing here with is a social circle of JOCKS.
Usually one grows out of it, eventually discovering that the quality of our lives is tied to the benefit of others.
Unfortunatelly, Michael hasn't grown out of it. When jocks discover they can no longer beat up people without going to jail, they do seek alternative ways of abuse. Soon they discover political means to do so, ie collectivist ideologies, which give them a moral right to force other people into servitude. Thus, a jock eventually joins one of the strands of modern collectivism, be it religious, conservatist or liberal. In theory their sport heroes get replaced by either God, Nation or Society. In practice however they all worship Government as the hero that forces other people to serve their goals. So no wonder Michael must obviously hate Rand's moral commandment never to sacrifice others to himself. He rants against "selfishness" so that at the end of the day he can enjoy a society molded and bullied by his hero Government. A society where our lives become "tied to the benefit of" Michael Gerson and the like.