and using the full name of the diagnosis instead of contracted nouns helps avoid using slurs and/or dehumanising the patent.

You got a typo there. Unless you can prove that said person was indeed diagnosed with such disability by an appropriate medical authority, let’s not use such term that could either be considered defamation, or at least medical disinformation.

People say what they intend to say, not what you wish them to. If you believe they are incorrect, no need to be pedantic about it. Just argue why, you’d find out people are way more open to arguments when they do not feel like you are condidering them as idiots.