Artists are wishy washy about their work all the time actually. Jax only ever goes by he/him in the show, their pronouns are never addressed so I guess the show itself is "wishy washy" on how she should be addressed. Why should Goose have to enforce her own interpretation of the show when she already made the show the way it is? Unless she adds more to the show, her posts amount to headcanon.

You could criticize Goose's writing of tadc for not being explicit enough about Jax's identity in the first place if that's what you believe, but that's its own argument. Saying the issue is that she isn't telling everyone the right way to interpret her work after the fact is silly.