I think we can only decide this issue if we include the perspective of the viewer. Imo the author would have written the same if he would have compared BHO to Moses, Samuel, Hesekiel, Jesaja, Salomo, etc.
If you are a very fleshy beeing, for you Obama is of cause the greatest, because Obama promises fleshy things to his followers and supporters. This kind of promises, like welfare, the right to laziness, sanctioning of homosexuality, apologizing murder-Muslims and other horrible things they will never get from the persons I mentioned abouve.
But if you are more spiritual, then Obama is for you the lowest of the low, because were he is, is not the Kingdom of God.
So it comes, that Obama is in the art of wickedness greater than every biblical author, but at the same time he is in the art of righteousness the lowest.