Would it not be a kinder and still realistic hypothesis that when the high school principal said he had been friends with a First Nations woman in college that he was simply trying to make a human connection with you?
Is it much different when someone identifies themselves as a Tajiki from Tajikistan, the other party says Oh I once knew someone from there?
Is it necessarily his fault that the only Oneida person he knows he met was from long ago? He probably has met several others since without knowing they were Oneida.
We can laugh a little at how it sometimes continues "Do you know so-and-so from ...", as if Tajikistan, Oneida, Onendaga, and (say) Rochester are not large communities.
I do not think there is an equivalency to the way Mrs Moore aped the famous line from the 1950s "Some of my best friends are negros" with their paraphrase referring to jews. The Moore's aping is definitely ignorant, period. Friendship with a few individuals does not exculpate racial stereotyping or racial prejudice (pre-judging members of a group simply for being members of a group).
I'm sure the principal was not using his memory as an excuse for racism. I could be wrong since I did not hear the conversation. There may have been something about the way you introduced yourself that made his remark inappropriate. Was he guilty of racial stereotyping?
Did he agree to help repatriate the remains? Has that effort been successful?