What hasn't been mentioned is whether he is an enrolled member of a tribe. There are more stringent blood quantum requirements for some tribes. That they haven't said, "And a member of X tribe... or X village tribal organization..." is pretty telling.
What keeps being mentioned is that he is a descendant of a Yup'ik woman (his mother.) I didn't connect with why this kept coming up in American Indian (Lower 48) commentary until I realized that, as Alaska Native people, this is a very common term because of the corporations. For many services or memberships, you can either be an "original shareholder" or a "descendant." If you were not 1/4 blood quantum Alaska Native in December of 1971 or before, you could not be an original shareholder--which is why, though I have more than the required blood quantum, because I was not born earlier, I am not an original shareholder. I am a "descendant." The frequent mention of his mother and of his being a descendant tells me that he is used to signing on as a descendant, not an original enrollee, which means that, despite him being born before 1971, he was not 1/4 or more Yup'ik.
To be very clear--I absolutely do not believe that blood quantum defines how "Native" you are. The frequent mention of it as a disqualifying factor is wrong. For that matter, there are countless ways to be a proud member of the Native community, and none of it has to do with that extra 1/16 more Native blood you have than the next guy over. What defines you as a Native leader, and a Native example, is much easier to nail down, and in this case, Todd would not be the definition of either.
He has also never been part of the Southcentral Alaska Native culture, nor have his children, despite being raised here. To me, this says he is either disinterested, or because he is limited in a few of the organizations (namely tribal) he is rejecting the whole. In any case, both the Palins have a dismal record on Native issues, so please, do not look to Todd's heritage to help with them. That he hasn't done anything because of it so far is a good indicator that he won't be encouraging his wife on anything in the future.