Goethe higher than Bach, Kant, Mozart, and da Vinci? What? Why? What a moronic project.
Much of this kind of 'forensic' IQ information is developed from the analysis of written material left behind, so it tends to produce scores that favor people who:
1. Wrote a lot
2. Wrote very well
The result is that such methods tend to overestimate the intelligence of professional writers (Goethe) while underestimating the intelligence of people who manifest their genius in non-verbal ways (it also explains, for instance, why Wagner outscores Mozart, Bach and Beethoven - he was a prolific and fairly talented writer, as well as a musician).
There is certainly value in IQ testing in establishing a ballpark estimate, but reality, as always, is the real test. For instance, it is obvious that the most intelligent person on this list is, in fact, the one who scored most poorly. Real genius is measured in accomplishments, and artists are no match for leaders in this respect.