The 1970 birthdate comes from the only located record of a Fiana Haarsma, which suggests she was born in April 1970 and lived close to Taos, New Mexico (hence the assumption that it may be the same woman). Of course, this would make her 55 this year, so it falls outside the suggested age range for the doe.
I'm finding it difficult to determine the age of the woman in the passport photo, especially since no further details have been provided. I would say the woman in the photo genuinely looks like she could be in her early 30s to late 40s, depending on how you look at it, but how old is the actual passport? The hair and other features don't immediately scream one specific era, so this could be a passport photo from this year or it could be from 20 years ago and out of date. I agree that it is odd/frustrating that more details have not been released especially as a passport would have quite significant identifying info on it.
Also, perhaps most notable, is the fact that we're all operating on the assumption that the passport belongs to the woman whose skull was found. Not only might the passport be a fake, but it may also not be the identity of the doe and/or the holder may be otherwise involved in the case