Anbuend, you have very good values and ideals, but it is unworkable to fight for all disabilities as a whole.
How could I possibly ascertain if all people affected by all disabilities wish to be regarded as a minority group?
Its very diffiicult to get opinions of the members of the autistic community that we have access to online. Most have chosen to express no opinion either way. How could I ask the millions of disabled people all around the world?

You said "It's like saying "We'll work for people with athetoid cerebral palsy first, and then maybe the rest of you later."
Anbuend, in the UK I couldnt possibly get legal aid and legal advice relating to an issue that I have no personal connection with, and I certainly couldnt pay to get legal advice for all disabilities, but I do have a chance of getting legal help for something that directly relates to me and my family. Its a very strong practical consideration.

You said "If I seem impatient or irritated, maybe it's because right now there's a crisis going on that may threaten my own life soon and I can't afford to be narrow about it."

I do understand.

You said "There is no international protection for, for instance, black people in particular (who are discriminated against in my country and some others). There is protection for racial and ethnic minorities."

Actually that is incorrect. If you look into the work of the UN, specific minority racial groups are protected. Look at those particularly in Eastern Europe as an example.