As a seasoned music afficionado I can listen to songs like this and many others whose message I don't agree with. I can even jam to them because they sound good. I'm secure enough with my convictions that no pop star is likely to shake them.
However, if Ludicrous thought he was advancing Obama's cause with this one, he missed the mark by a long shot. Calling people you disagree with irrelevant, gutless, or wishing them paralyzed may make for good rap lyrics, but it's not going to win anybody over. A national election is not a high school party.
Americans want a lot of different things from their president. What they absolutely don't want is a president who seems to have an ax to grind with the majority of the population. This kind of thing feeds exactly that sentiment, whether it actually fits Obama or not.