Ms Cleo also makes predictions which have been proven after the fact - does that make her a great scientist?
The answer is no. Predictions are scientific proof only when all the predictions are proven to be true. Any charlatan can make some predictions that turn out to be true - and Darwin was an excellent charlatan. I have shown some important predictions of Darwin, pretty central to his theory that have been proven false: brachyocephalism, melding of parental traits, proof of evolution from the fossil record, the malthusian basis of evolution, to name just some. So no, his predictions prove him a charlatan, not a scientist.
The big difference is that the charlatans make predictions using fuzzy wording so that they can shape almost any event to be construed as fitting their predictions. The predictions are also alone, that is independent of each other, or anything for that matter.
Darwin set up a scientific framework and said that for the framework to be true, these things must be found. He stated specifically, and did so within the framework. That some predictions were wrong shows that Darwin didn't know everything and that as we know, evolutionary theory has far surpassed him with advanced knowledge and new discoveries.
On your personal attack line, I also don't discredit Blaise Pascal's math genius because of the logical nightmare that is his "wager."