It asserts the two are uncorrelated, not that the two are anticorrelated. But I agree, data regarding this theory would be great. It is not immediately obvious how to come up with more informative data than what is given though, because the ill defined questions necessarily have ill defined answers, so any data will be heavily determined by subjective judgement. Nevertheless I think you are too dismissive. The basic premise is that most intelligence measures we have concern well defined tasks, so it is interesting to explore the relationship between intelligence and ill defined tasks.