I would say this is more like being told “No prejudice” at Thanksgiving Dinner, and then being thrown out for saying that mashed potatoes were a mistake of god.

It is technically prejudiced (against mashed potatoes), but it is not the assumption most people would have upon being told “No prejudice”. Likewise, being told “Don’t discriminate against anyone’s gender identity” does not, for many, call to mind “Don’t say people can’t be dragons or that dragons aren’t real, they can be dragons if they want”.