You disagree with the definition? Aren’t you the crowd who likes to put up billboards of definitions or wear definitions on tshirts?

Yes, the "GC" crowd disagrees with the definition(s) you've given so far. First you said,

Gender non conformity is when someone's gender falls outside of the two binary genders, man and woman. So agender or bigender people are gender nonconforming (but there are many other types of non-binary genders).

Sorry, but to most people this comes off as gibberish that's incoherent & nonsensical coz it relies entirely on circular definitions. In your first sentence, you resorted to using the word gender three times, all without saying what gender means to you - & it wasn't a very long sentence. In your second sentence, you did the same, only in that case you used the word gender four times.

But you did slip in that there are "two binary genders, man and woman." Since man & woman denote human sex, most people reading what you wrote would therefore conclude that to you, gender = sex. In another post you said,

In the case of gender identity it means your personal sense of being male, female, or neither

Which again gives the unmistakable impression that to you, gender means sex, because male & female connote sex.

This is a fundamental area on which the QT crowd & the GC crowd differ. GC sees sex and gender as separate & very different to one another. We see sex as a biological, material reality, an inherent & immutable fact of our species & of every human life that's determined by nature long before each individual is/was born. By contrast, we see gender as sex stereotypes, as socially-constructed ideas & norms that human cultures have come up with & imposed on the two sexes, male & female.

Since the time our species came into being, the characteristics of human sex have remained steady - the biological features that make someone a boy/man or a girl/woman, and which distinguish the two human sexes from one another, have not changed over the course of human history, although understanding of, & names for, these features have evolved & changed considerably. However, the ideas & norms that constitute gender & determine whether someone is seen as masculine or feminine, and neuter or androgynous, in a given culture at a particular moment in history, have changed greatly over time. Moreover, the ways masculinity & femininity are defined within the same historical era often vary between different cultures and from place to place on earth, or even within the same culture or country.

We see gender in the way the term long has been used in grammar in certain languages, as referring to whether someone or some thing is masculine, feminine or neuter.