So you say the obese aren't their best selves, but that you don't care, because they aren't you or your SO, right? That's still not the same thing as saying "the concept of best self can only be applied to oneself". That's very clearly saying "I am judging all these obese people as 'worse' than their 'best selves', but I don't care."
So which is it? Judging others or not judging others?
I am not judging people I am not even thinking about.
OK, then your answer to me, when I asked you if I was my
best self, really doesn't make sense, and neither does your statement that "Obese people are worthwhile people. They are not their best selves when they are obese."
You're saying that you make these judgement about others, but it happens very rarely because you don't associate with fat people and therefore do not have to consider them.