That's irrelevant. All that the OP's point requires is that, on average, the moral choices of such people are worse. The existence of outliers -- or even common exceptions -- does not refute that.
My frequency of lawbreaking would indeed (anti-)correlate with the quality of moral decisionmaking, and my frequency of lawbreaking is likely lower than those who have been convicted (at least if severity-weighted).
Further, the comparison was against convicts, who do it frequently and severely enough that someone finds it worth the money to prosecute and get a conviction. And at that point, yes, a correlation appears.
You're still making the same fallacy: "I can find an exception, so the correlation doesn't hold." That doesn't follow.