Enby Skeptic
An individual, typically a part of the LGBTQ+ community, who is skeptical of the validity or even the very existence of non-binary gender identities, and sometimes uses that skepticism to exclude non-binary people from said community. It is also called non-binary skeptic.
"This LGBTQ+ event is open to everyone in the community, including enbies! Enby skeptics and exclusionists need not apply!"