There is nothing wrong with saying autism is a disability. You can't be diagnosed with autism unless you are impaired by it. Autism as it is defined is a neurodevelopmental condition that impairs the person who has in it many ways. Just like there is nothing wrong with saying flowers are plants by definition. Or that humans are by definition mammals and reptiles are not.
Autism is by definition an impairment and therefore a disability, and there's nothing wrong with saying that.
The Japan Federation of Landscape Contractors organizes an annual landscaping contest, where landscaping contractors from around Japan arrive on site with their mini pickup trucks and then spending several hours transforming the cargo bed into a small garden.