I know nothing about that statement. There are are threads on this forum about AMR failures due to the O ring getting squished, hence Jim Comstock’s comment.
Regardless, I can agree that it is best not to have anything in-line between the oil tank and the pump.
I have, however, had a RGM check valve on my ‘74 for 14,000 miles without engine failure and removed it after installing the Comstock Sump Breather which takes care of wet sumping. Glad to hear your bike never wet sumps. Your purity is an inspiration.