So now that you've made your opinion known, here's mine:
So what? It is a political cartoon and if you are stupid enough to take it seriously; you weren't going to vote for Obama anyhow. I understand what the Obama campaign has said, I just flat out don't agree. Low information voters are one thing, people who take this stuff seriously do so for their own reasons.
The readers of the New Yorker are a fairly select group so the reading part of it will be them and not the low information group. The idea seems to be they'll see the cover on a news stand and take it from there or see it on the news. If it is on the news and the sound is on...? That kind of leaves the argument resting on the news stand. A person sees this on a news stand and thinks...what? Oh this cartoon just verified my worst thoughts after getting that email or hearing about it? Oh, pshaw.