Perhaps I just engage more when Veganism comes up within Antinatalist circles, but I'd like to point out two types of people who get to me whenever it is brought up.
These two types of people represent an incredibly small minority of the Antinatalist community, yet their excuses and debates garner the most attention.
Right now I know of no medical condition which 100% prevents a person from going Vegan. Do some conditions make it significantly more difficult? Absolutely. The rub is that it is ultimately irrelevant, and that even if there were conditions that make it impossible for a person to eat a 100% plant based diet, that doesn't effect the ethics of the situation for the vast majority of other people who can go Vegan without medical issue.
Yet, these people are always at the forefront of posts on the Vegan debate whenever it is brought up, and other people use those people as an excuse for why they can't or won't go Vegan, despite being perfectly able.
These people, and their reasoning, is laughed out of the room in almost every other area of Antinatalist ethics because it can easily be used to justify not only any unethical action, but Natalism as well. Yet, they are given a pedestal and the keys to the kingdom when it comes to the Vegan discussions.
Also, Antinatalists seem to do a complete U-turn on debate etiquette when Veganism is brought up. You'll see it time and time again when a Vegan argues in a completely calm and rational fashion, but is met with accusations of being angry, accusatory, morally self-righteous, and let's not forget the infamous, "shoving their beliefs down people's throats".