Are they implying dual personality? Male/female?
= = =
Writer and editor are incompetent. They assume ‘Olympian and activist’ as a plural subject, requiring a plural pronoun. Just typed it up and it sounded OK.
Did get the ‘was’ right.
“Former Olympian and transgender activist Caitlyn Jenner was on The View Wednesday to talk about their new book and how they...”
Or, there were no red-underlined words so it MUST be correct.