No. first of all you have no idea if the author had a preconceived thesis. As I see it the methodology flattens discrepancies between counties
Secondly, the fundamental conclusion, which you clearly don't like because of your preconceived notions, would change not a whit regardless of methodology.
Why?
Key phrases: lower income and how much each county receives.
You're getting back more than you kicked in. Period.
“The lower income regions of Illinois as a whole are receiving significantly more in state expenditures than they contribute in taxes,” the study wrote. “Indeed in the most southern region, there would be very little economic activity at all without the state.”