"Autism isn't a lifestyle, it's a severe psychological disorder."
No. Autism is a neurodivergence and a disability and it is a lifestyle.
My everyday life, how I cut and style my hair (or don't), the clothes I wear (or don't), the food I eat (or don't), the social life and relationships I have (or don't), how I spent my holidays (or don't), the books I read, the music I listen and dance to, the interests I have, how I communicate, my worldview, my financial situation, my sleep (or lack of), all this is part of being autistic for me.
Several things can be true at once.