He replied, "I don't think I'm wrong."
I said, "Of course you don't think you're wrong. The operative condition of being wrong is you don't know it. So you're exactly where you should be, as someone who is wrong."
Since I never speak this way, he laughed and said, "Okay, how am I wrong?"
So I explained it. He accepted my explanation and agreed that the copy had flaws and said he'd fix them. And then he vowed to get even the next time I was wrong. So it all worked out. And I doubt he'll have a long wait before he evens the scales.