I added LM MoS2 on a couple occasions to Mobil 1 5w40, 1/2 of a 300ml container each time, mixed with about 4.5 quarts of oil. The used-oil results showed reduced wear metals, not only during the initial OCI but in the follow-on interval.
Mobil 1 0w40 contains moly, 5w40 does not -- presumably because it's already a top-quality oil which may not need the moly or because it would increase the cost of manufacture. But based on my limited experience with MoS2, I would consider it a useful additive -- in small quantities -- when used with an oil which does not come from the manufacturer with a moly additive.
I would not describe LM MoS2 as snake oil -- it is molybdenum mixed with a harmless base. I do not know of any harm that can come from using it.