When I was in college, about the same time FLEK got her Idaho ID, there were several books circulating on campus about how to disappear. Apparently, when grave tripping it was suggested that one pick a name with a birth date close to your own. If FLEK was working from such a book and following it to the letter, that may be why she chose BST.
On the other hand, according to the Seattle Times article, one of her physicians seemed to think that her attempts at pregnancy may have been complicated by being older than she claimed. I would assume that the physician may have better grasp on her age than a layperson.
Then again, if she was born in the early 1950's wouldn't that put her in her 50's trying to conceive? (Math is not my strong point.) Not impossible, but definitely on the edge. My wife is not yet 50 and she's already gone through menopause.
I'm just having a hard time accepting the idea that she was much older than BST. She appears to have done every other part of her identity change "by the book." Why not assume she picked BST by the book as well? This could be the case even if she used an identity broker.
Speaking of identity broker, perhaps that's why no one "recognizes" her. Back in the day there was apparently a national network set up to free abused spouses/children from harmful homes. Shedding light on an identity broker, and subsequently a network, could expose other clients to danger.
I wonder how such networks are viewed by law enforcement, if they still exist. (I recall reading an account of a woman accused of leading such a ring circa 1992.)