It means what ever the fuck they need it to mean at the time. It's supposed to mean something like what you can find on your first google search: "Ableism – are the practices and dominant attitudes in society that devalue and limit the potential of persons with disabilities." It's really complicated in how stupid it is. It works kind of the same way that the concept of Fatphobia does. When people fight against supposed Fatphobia, they are essentially trying to rid themselves of any consequences or personal responsibility. They don't want to face the limits imposed upon them by their own fatness. Those who fight against Ableism are essentially doing the same thing. They refuse to recognize the bad culture of coddling that has ruined many disabled people before they were even given a choice in the matter. They consider any attempt to hold disabled people to proper standards as "abliesm". Fuck, the entire term turns disabled people against disabled people similar to how moons and planets will turn on each other in the fatosphere.