Language configure the way you think. And words and symbols carry meaning beyond your intended "meaning". So while the swastika used to be a "spiritual symbol" for Indians, it no longer means that. Nazis make sure that we associate swastika with a genocide. And doesn't matter how much do you want to use it as a symbol of spirituality or peace, when people see it, now it means hate.
Your use of the word "retarded" just proves the opposite of what you were trying to argue. Because when I read it, what I think is that it is way less accurate than "neurodivergent" and also carries "weight" and is offensive. I mean, by your criteria, men like Elon Musk should be called "retarded" because he has admitted he is neurodivergent. But you won't use "retarded" with Elon Musk since he is deemed "successful" and has many fanboys. XD
Sure you can reclaim words, but dog whistles are a good way to identify hateful people. And I would advise to quietly "ghost" that hateful people, since not only that is safer for you, it denies them the audience they crave and people to abuse.
If you really, really want to reclaim words, twist them. Use the same expressions like "snowflake" to refer to them. After all, they always expect special treatment and are really fond of "white" so it is fitting. XD
On the other hand, words like "mansplaining", "misogynoir" or "Heteronormative" do have power, since now we can name things that have always happened but we have difficulties to talk about because we didn't have the words for it. With your example, neurodivergent, is way more accurate and better, because it describes the reality of those people. Neurocatch updivergents aren't "retarded" just different and for some things they do have advantages. But we don't go saying that "nondivergents" are "retarded" in the areas where divergents have the advantage, do we? XD
I do get that sometimes we are angry about injustice, but prioritizing respect is always a good idea. And don't worry, there will always people like me perfectly able to annoy the "mean girls" without using their slurs. After all, they have very small lifes and real life always catch up. XD
