Mr Musk had initially rushed to embrace the news when Jenna, formally known as Xavier, transitioned at age 16.
To me this suggests that he first thought it would seem hip and contrarian to support his trans daughter, then he realized that actually the people he considers hip and contrarian are all about hating on trans kids now, and so swiftly pivoted to doing that. (I don't imagine he had any strong feelings about his daughter as a person either way - it's not like he was around for her childhood changing diapers or whatever)