He also called the case "the most extraordinary hype and exaggeration in the history of the justice system," which is itself an extraordinary exaggeration.
It's hard to find a good account of what McMahon's argument really was. The NYT article gives a better hint at the legal substance of it:
The doctor’s defense lawyer, Jack J. McMahon, argued Monday that none of the remaining four cases had resulted in live births. Because the women were given injections of the drug digoxin, which causes “fetal demise,” Mr. McMahon argued, any postdelivery movements were involuntary spasms.
“Every single piece of scientific evidence in this case has shown stillbirth,” he said.
But Edward Cameron, an assistant district attorney, countered that testimony showed Dr. Gosnell did not always use digoxin and that it did not always work as intended. He quoted a former clinic worker with medical school training but no doctor’s license who testified that the drug “wasn’t giving the desired effect, the heart was always beating.” The prosecutor cited Pennsylvania law stating that if a baby delivered during an abortion “shows any sign of life, it’s considered alive — a heartbeat, breathing, a cry, movement.”