I feel this is a very ambiguous ideal that could use a little clarification. As a comparison, if a straight person didn't want to support a strictly heterosexual narrative, they could avoid assuming someone's SO was opposite sex. They could avoid using the compliment that an attractive person could have their pick of anyone of the opposite sex or that everyone of the opposite sex must be attracted to them. If they were a writer (ads, shows, etc.), they could include a gay couple in their script or book, even if the role was minor, just to reflect the real world.
So, how does someone who happily fits into the gender binary not support it? It seems this a more far-reaching, difficult-to-attain standard. I almost feel people want me to *not* fit into the gender binary to oppose it; that's akin to wanting a straight person to not fit into the heterosexual narrative instead of simply being inclusive of gay people. Imagine pressuring a straight couple to use gender neutral figures on their wedding cake. If they want to do so as a supportive message, that's wonderful, but they shouldn't be made to feel guilty if they don't.