He does not know it all! There are no magic chemicals in non-synthetic that will “seat” the rings. On the contrary, regular oil is less slippery than synthetic and will cause enough initial wear on the cylinders and rings to seat them properly so the car does not consume any oil later.
But, as others point out, today’s engines are much more precision manufcatured so that this initial seating is less important.
Having said all this, my Toyota dealer recommends synthetic after the 2nd oil chnage, which would be at 10,000 miles or so. They make a lot of money on synthetic oil, but still recommend it not be used right away. Personally, I recommend one regular oil change and then synthetic; some engines still require some “wearing” in.