I bet you could change the results
If you were to choose different male and female names, I would bet that the results could be closer together, if not reversed. Would an "Elizabeth" or "Margaret" have fared better, perhaps? Suppose the male name was of the diminutive sort, say "Johnny" instead of "John"?
This certainly seems to be a valid study, and I would like to see hiring managers all over the country made aware of it.