To be fair, that's not what Cham said. One of the main reasons Obama got elected is because of how ill informed and uneducated the vast majority of our populace is. That doesn't mean those that voted for McCain or Romney are smarter. One doesn't negate the other. I can pull up silly, uninformed comments by Obama voters as well. Hell, there is a slew of people who still blame Bush for the recession no matter what the evidence shows.
This is a horrible idea, but to be fair I don't think that's quite what Obama was proposing. He did mention countries that have mandatory voting AND he spoke about how transformative it would be if everyone voted, but he did stop short at actually saying we should have mandatory voting. Honestly there are millions of people I would rather they not vote, and it would be unconstitutional anyway.