>
> By the time of the Third Imperium, there are no longer any truly
> pureblood Terrans.  There are just those who might like to claim such
> a thing.
>
In imperial space most likely, but what about on the rimward side of Solomani space? The Ziru Sirka didn't push that far, so apart from scattered and isolated minor human races, there could be significant pockets of descendants of Solomani who've never encountered another major human race.