Read the article. It CLEARLY states she was 18 at the time of the incident.
Read footnote #2 in the Motion to Compel Production of Evidence from Third-Parties, on which the article's 'ah-hah!' moment is based, and which is underlined in the article.
"Witness is 18 years old and was 18 years old at the time of Crump's interview of her[.]"
Nothing in the source document for the article says the witness was 18 years old at the time of the incident.
Now read the article again. Where's this "CLEARLY" of which you write?.