From the article, she admits being listed "as a minority in a directory of law professors" from "1985 to 1996". Then she "was granted tenure in 1995 – [the employer] touted the Democrat’s Native American background as part of an effort to boost its diversity hiring record".

So, she publicized herself as a minority. Gets tenure with the employer touting her minority status. Then, she stops calling herself a minority. I think that's pretty convincing she used her false minority status in order to get the job, ie affirmative action.