Remember he met with only one "tribe" as far as I know. Just think what he might have said if he had met with the other Original peoples of Turtle Island and around the world! My heroes, the ancestors, too many to mention, have never left the paradigm of Native thought because it is a source and not a resource.
Now if you think about the world these Native children were experiencing and how little of the western educational experiment they were exposed to, then it makes sense from the get-go - how long they were already living 'in Relativity' rather than the 'Theory of' it. In other words, they had no western education from the day they were born until the time they met Einstein, a westerner!
Just think if he had met more than one "Original Nation" rather than one 'tribe' ???