What percent of blacks, then, are over 18? If it were even two-thirds (it's not), and then applying your dream of 33% of those folks going for Ron Paul (they won't), the numbers are still too few to lift your candidate out of 'Ralph Nader' territory.
Don't let math discourage you though. Imaginary numbers should be no problem at all for the witch-shrunken heads of Ron Paul & company.
Ignoring for a moment the question of whether or not these polls are accurate, you are wrong about there not being enough Black votes to matter.
After the 2000 election Karl Rove spoke often about the 4 million Christians who didn’t turn out to vote. He made a big push to get them out in 2004, including an unprecedented push in Black churches hitting the issues of abortion, gay rights, and gay marriage real heavy in the churches.
The strategy paid off. In 2004 Bush won more than double the number of Black votes in Ohio as he won in 2000. The 14% of the Black vote he won in Ohio gave him the state and the election. Had he lost Ohio, the Florida vote would have been meaningless. We would have President Kerry today.
The election is not won on the popular vote it is won in the Electoral College. In several key states, like Ohio, Democrats can’t win the state without getting 90% or better of the Black vote. Ed Rollins knew that and went after the Black social conservatives in Reagan’s 1984 landslide win. Rove followed that lead in 2004 and saved the election from going the other way.
The Democrat Party leaders wet their pants when they see the Black vote slipping anywhere. Any Republican candidate that can pull more than 10% of the Black vote is an odds on favorite to win the Presidency.
None of this is saying that I’m convinced that Dr. Paul can win that much of the Black vote. However, if he really could pull more than 20% of the Black vote he would walk away with the election.