What exactly is an anti-vegan? I ask, because I don't really know anyone who is anti-vegan. Do you mean ex-vegan, or people who are offended by vegans?
I live in California, which is a pretty liberal pro-veg, pro-health, pro-vegan place. I'm not anti-vegan. I've got probably 20 vegan cookbooks and I love vegan food. I have vegan friends.
If someone who has never been vegan is spreading information about "mysterious illnesses and lack of minerals" (or whatever), then of course, take that with a grain of salt.
However, if someone is an ex-vegan, or ex-vegetarian because they got sick - well then, I'm going to listen. Am I going to probe to make sure they did it perfectly, or exactly right, or ???
No. I trust that my friends, who were caring enough about animals and health to go veg or vegan in the first place, are going to do all they can to "stay the course". And for all intents and purposes - they did - including (probably not limited to), talking to dietitians, doctors (of various types), attempting injections, tweaking their diets. And...it didn't work.
A vegan suggesting that they "didn't do it right" is ridiculous and maddening because ... they weren't there. All this nonsense of "I've never seen a documented case"...like a doctor working with one or two patients who have the issue is going to write a paper on it. I mean, really. Pretty ridiculous. We aren't talking university doctors or large medical centers where they are running studies. We are talking a doctor at the local clinic seeing a regular patient. Or perhaps a specialist who took over on referral.
So what is "enough"? Is it a year? Is a year of poor health and loss of a job enough? Should it be two years? It's sort of like the sliding scale of breastfeeding, and the breastfeeding nazis. "Try this", "Try that", "did you do this?" "did you try that?" "Clearly you are doing it wrong." "Oh, you aren't making enough milk? You are probably lying. You are too lazy. Don't give formula. That's a cop out. If you nurse and pump every hour and take X/Y/Z you'll make enough milk." Blah blah blah.
Fact of the matter is, everyone has an opinion, and it's up to the individual to decide that enough is enough. If the baby has lost a dangerous amount of weight, it's a no brainer. Give them formula. If you've been sick for months or years, and shots don't work, try meat. Does it work? Great.