I think that this focus on the name -- in particular, the attitude, "I'm vegan, but this or that person shouldn't be allowed to claim the vegan label" -- is a major reason why veganism is still a fringe movement. Successful movements are inclusive. They want to take over the world, and they recognize that in order to do so, they need to accept and include people who come from different backgrounds and philosophies. Too many vegans, in contrast, behave so as to keep veganism as pure, as exclusive, and, as a consequence, as small as possible.
The idea that someone who is vegan for health reasons should not be called vegan ignores the reality that people change. A person who stopped eating animals for health reasons is much more likely to recognize and embrace the ethical and environmental aspects of veganism after six months of avoiding animal products than a person who ate meat for those six months. Telling that person that they don't get to use the vegan label alienates them and makes them less likely to embrace the other aspects of veganism. Allowing that person to use the vegan label does not in any way make me less vegan or in any way decrease my concern for animals and the environment. Vegans don't need to feel so threatened by other people less pure and less perfect than they are using the vegan label.
When I went vegan, I did so for the animals. I wasn't concerned about my health, which I thought was excellent. What disturbed me was factory farming. I didn't have a problem with the idea of eating animals, if the animals were "treated well." But since animals were not treated well, I didn't eat them, and I did my best to avoid using them in other ways. Over time, my views shifted gradually, at an almost imperceptible rate, so that at some point, I no longer saw animals as a source of food. The whole idea of eating animals began to seem unnatural and wrong. Similarly, in my early days, since I was focused on avoiding harming animals, I didn't have a problem with eating animal products once they had been served. If I had ordered a vegan spaghetti without cheese, and it came with cheese, I would eat it because the harm had already been done, and sending that spaghetti back would only harm the environment further by causing waste. It was after I came to recognize the health reasons for veganism that I got to a point where I would be very reluctant to eat that spaghetti. The different aspects of veganism fit together. A person may come to veganism from one angle or another, but in the end, all vegans end up in the same place of love and compassion for all living beings.
I don't even have a problem with someone who eats meat once a year calling themselves vegan. And the reason for that is that I have more confidence in veganism than most vegans. Those who would refuse to call that person vegan are conceding that there is something good and desirable about eating meat. I do not. As Peter Singer has said, if eating meat once a year is going to keep someone vegan for the rest of the year, that is good for animals and the environment. Moreover, that person who didn't eat animal products for a year is not going to want to eat meat on the occasion where he is allowed to do so. It's not going to taste good; it's going to make him sick; it will seem unnatural and wrong. And who wins as a result? Animals do.
For a long time, I avoided the vegan label because I did not want to have anything to do with the purist, self-satisfied, and exclusive aspect of the movement. This caused a lot of confusion because the public doesn't understand why a person who doesn't eat dairy and eggs is not a vegan but only a vegetarian. Trying to explain it to them only gives them the impression that vegans are crazy. After years of calling myself "vegetarian", "strict vegetarian", "plant based", "vegan but not like the vegans you're thinking of," I finally decided that I cannot let the self-satisfied purists who care more about themselves than they do about animals define veganism. In the end, this is about the animals, and animals don't care why you're not exploiting them and what you choose to call yourself.
"Those who would refuse to call that person vegan are conceding that there is something good and desirable about eating meat." ....no...no that's actually not what's happening here...if someone only committed rape once a year, I'd still call them a rapist. If someone only committed murder once in their lifetime, they'd still be a murderer. Someone who eats meat, ever, is not a vegan. It's quite different for someone to eat some cheese accidentally stuffed in their restaurant burrito or to accept a piece of bread that has whey in it than to eat meat. Sure, that person only eating meat once a year is better than eating it every day, but NO, saying that they aren't vegan isn't the same as conceding that there's something good or desirable about eating meat. Where the heck did you pull that from?
Also, people like you who want nothing to do with other vegans aren't capable of acknowledging the huge legal cases PETA has settled, the businesses that have been shut down, the factory farms that have been burned by ALF, the animals that have been rescued by "extremists."
The Civil Rights movement required both Martin Luther King Jr and Malcom X. If you say as MLK that you think Malcom X isn't helping others then you're being disingenuous and petty. Both types are needed for ANY political movement. Early feminists threw stones through windows and put bombs in mailboxes, you can't possibly be serious.