Ring gaps do not necessarily remain in the orientation in which they were installed, so not sure how he knows that is the case. In theory they do not see rotational forces, but I have certainly seen engines torn down that I know were installed properly only to find the gaps not where they should be.
There are a few things that can cause improper seating of rings. Babying the engine too much during break-in is the most likely. Rings seat MUCH better if run pretty hard (full throttle, high gear, low to medium RPM) for stretches of highway, then run easily long enough to get everything cooled back down, then run hard again. Most people take it TOO easy on the engine right out of the showroom thinking they will hurt it, when the opposite is true.
Also a debatable topic is oils used. Some say synthetic oils used too early can hurt ring seating, but as I said, debatable. Whatever you want to believe here is proven beyond doubt on the Internet!
Certainly putting "miracle" additives in the oil before broken in can cause problems. For rings to seat properly to the cylinder walls, a lot of combustion pressure to force them out is needed, along with sufficient friction to "wear" the surface in, but not so much heat built up as to glaze the oil film, then you have a problem that can only be solved by a "glaze breaking" hone, but that is not recommended by some experts on NikaSil coatings.
I am not at all surprised that your mechanic found excellent cylinder walls. That is a trademark of the BMW motorcycle engines. BMW had a lot of trouble with NikaSil their cars in the late 80s, blamed it on the high sulfur fuels in the US. Funny, Porsche, Mercedes, and even BMW motorcycles had the same coating, but did not suffer. Of course, it could not possibly have been a process problem at BMW on just the car engines during that time, now could it?
I would love to know if your mechanic runs any type of glaze breaking hone in the cylinders before putting in the new rings. I have read about 50/50 opinions on any type of honing on NikaSil, curious to have another data point.
I used a "ball" type hone just to clean the surface on mine when I put the new pistons/rings in, but was worried whether this was the right thing to do, read so many things both ways it was a 50/50 shot.