Fair enough, and I'm sure that when Japanese nationalists talk about Japanese as a race, they probably mean Yamato, but that doesn't make it accurate to describe "Japanese" as a singular ethnic or racial identity.
It isn’t accurate but nor is it exactly wrong. The word is very contextual. Most nationalities can be construed into races, and many things we considered race today arose from nationalities a long time ago (in the long run they blend together).