She was hired to do this. As explained in the article, the company wanted to test their own security. She is able to revel in her deception because it's exactly what the company wanted from her.
>If you don't believe her that she was hired, why believe the rest of her story?
As a matter of fact I don't believe most of the rest of the story, and - for some reasons - I have been downvoted for expressing my doubt of it sounding "too good/easy to be true":
Maybe I should have called it "not very plausible overall", as there is IMHO too much contrast between the described "high security" context and the extents of what the pentester has reportedly been allowed to do once gained access.
