As a late-comer who just read through the whole thread, there is one thing clear- Nova P is a freakin' hero. I've always had some respect for her for participating in and enduring the male-dominated world of DGCR, but damn I am so impressed and even inspired by her indefatigable courage in speaking up for the oppressed.
Also, here's some non-opinion facts which I've learned from science and having a degree in some science stuff that included some neuroscience and developmental:
Not everyone is born "XX" or "XY." Some people are born XXY, some are born XYY. Both usually look male (XXY looking a little more culturally stereo-typically female, or androgynous), and it's not super correlated with transgender, but the idea that people are either born XX or XY is not correct.
What is also not correct is the idea that everyone is either born with male or female genitalia. Ambiguous/Co-existing male and female genitalia at birth is so common, if you went to a high school with more than a couple thousand students, you probably had a couple as fellow students.
Simile, it has been mentioned how gender is determined by hormones present during gestation, but to further illumine that process, imagine this: The default position for every gene is female, the gender which reproduces. At certain stages of development the presence of a Y chromosome (which is really a slightly broken X chromosome) activates a "switch" that determines whether male characteristic develop, and the female remains dormant. Most development happens in (and this is really painting with a broad brush here) a cascade scenario, where activating the male switch in a certain trait can turn on the male switch for the next one, which continues the process until you have a fully male organism. At any point, this process can break and the rest of development continues as female, or it could skip and you get mixed development. But the default setting for genes for practically EVERY LIVING THING in the animal Kingdom (especially the further you get down the taxonomy tree) is female.
I hope that clears up now absolutely unclear and unabsolute the issue can be.
For my opinion and my stance- I always err on the side of compassion and validation. Even if it means I can sometimes be taken advantage of. I would always rather someone feel loved and seen than protect my own ego, and don't want anyone to experience real pain that I as someone who presents as just a regular white guy will never know. I don't think this is a huge issue in disc golf, but one of my old college friends who I used to play with transitioned, and if she competed now (which I don't think she's picked up a disc since we played together) I would only encourage her to pick the division she felt comfortable in, knowing she's still a fair competitor with integrity who just wants to participate.
TL;DR: Nova P is a hero, development is wonky, and love goes a long way.