She doesn't need to be proving that leg hair is good or healthy to do a logical fallacy
She does need to be doing that if you want the logical fallacy to be "appeal to nature fallacy".
that's not saying the same thing twice
Tatutology is when two seemingly different statements carry the same information. The two different statements in "They are supposed to be there because that is where they naturally are" don't actually say anything much different. If "naturally" was to be replaced with "normally", then it would be a complete tautology but I only said a bit of tautology because "naturally" contains more information than "supposed to". But the whole point of my argument is that I think she is using naturally in lieu of "normally" rather than as a precursor for healthy or good.