George Will is very uncomfortable with the idea of automatic voter registration or even the idea of more people voting, and here he is explaining why.
Because the likelihood of any individual’s vote mattering is infinitesimal and because the effort required to be an informed voter can be substantial, ignorance and abstention are rational, unless voting is cathartic or otherwise satisfying. A small voting requirement such as registration, which calls for the individual voter’s initiative, acts to filter potential voters with the weakest motivations. They are apt to invest minimal effort in civic competence. As indifferent or reluctant voters are nagged to the polls — or someday prodded there by a monetary penalty for nonvoting — the caliber of the electorate must decline.
Which group of Americans are disproportionately effected by making it more difficult to register and more difficult to vote? Minorities.
According to Will, these people have the "weakest motivations" and are only willing to invest "minimal effort in civic competence." And if we register all of them to vote, the "caliber of the electorate must decline."
As someone who lived in an overwhelmingly-white red state for 27 years that, on the best of days, may see registered-voter turnout of 20 percent, I can tell you that the caliber of the electorate can only improve. It can't get any worse. And those with the "weakest motivations" are already voting in droves. They're white, they're registered, and they're voting because socialism!
Of course what specific motivations Will has in mind aren't clear, but I think it's safe to assume he's implying that too many voters would feel compelled to vote for more free stuff and hand-outs if we automatically register them. He believes we should make it as hard as possible to vote for your own self-interest and that it's better to have a milquetoast electorate that, almost categorically, votes against their own self-interest.
In his mind, such people aren't of a high enough "caliber" and have no business voting.
I can't discern if Will is glossing over his own racism with this call for a master race electorate, or if he simply abhors poor people. Not that one is necessarily better than the other.