Kauffman foundation is a conservative group (certainly not as much as, say, Chamber of Commerce, but it's right-leaning), so they will cherry-pick the data points that advance their policy recommendations

You might be right, but critique like "does not match actual real life experience" is cheap and might as well be "doesn't conform to my selection bias". From doing my own comparison it seems clear that in companies with big exits, a high level of education is very common. This doesn't necessarily mean that a high level of education is better for making large companies, but does challenge the picture of the entrepreneur as a dandelion child.