Don't worry xsledder, i read that article and several other economists rebuttals to the study, i cover my basis. But you didn't read the entire article. If stated right after that "However, given the study design, Holmes points out "my results do not say that it is right-to-work laws that matter, but rather that the 'probusiness package' offered by right-to-work states seems to matter".[8] Moreover, as noted by Kevin Drum and others, this result may reflect business relocation rather than overall enhancement of economic growth, since "businesses prefer locating in states where costs are low and rules are lax. Due to other similarities between states that have passed right-to-work laws, it is difficult to analyze these laws by comparing states; for instance, right-to-work states often have a number of strong pro-business policies, making it difficult to isolate the effect of right-to-work laws." So it goes back to the politics of how the area or the deals that can be struck with an area, hence a TIF or other means also, as i stated earlier.
One thing, I am not arguing for Unions, just pointing out the vast issues involved.
Also read "Studies of Economic Impact" below your citation. Lastly, although we are using it here, Wikipedia is not exactly a good site to use as a source.