Are you serious? Surely no one is THAT dumb!
First (and it'd difficult to know where to start), It's very rare to come across anyone posting on a site like this who appears to be "anti-vegan". There are lots of people (>99% of the population) who are not "pro-vegan" and plenty of people who are concerned at the rubbish posted by a few vegans on sites like this and on the internet in general, but even they are quite happy for veganism to exist and for informed, sensible adults to be vegan.
Second, generally, no one claims that the vegan diet is "dangerous" but what is claimed, and accepted by many vegans, is that a person who decides to "go vegan" risks health problems long-term unless they research the subject and ensure that they obtain the necessary nutrition that they no longer obtain from meat and animal products. I have seen MANY vegans give this advice. Simply stopping consuming meat and animal products is not sensible or healthy.
Third, do you understand what "sue" means? How would it work in the way you suggest? Do you think the publishers of a dictionary could be "sued" if they included the word "vegan"? On what grounds do you think YA could be sued?
You seem to be implying that, because YA includes a category then it can not, under any circumstances be dangerous. Clearly this is ridiculous. Beer, Wine and Spirits can be dangerous. So too can cars. I do not know if there is a catagory related to weapons such as guns and knives but any newsagent in the UK will sell magazines on guns of one kind or another. Tobacco products are freely available and yet are known to be dangerous. You seem to have little experience of life and appear to be rather naive.
Finally, apparently you do not know what bullying is. If I was to post "lies" about veganism I am not bullying anyone. If I was to claim, for example, that no vegan can be healthy (and I do NOT claim this) I am not being a bully. The word "bully" does not mean "a person who tells lies".
Like I say though, I doubt you're serious!