If the driver is unable to handle the service for a reason related to the disability (e.g. wheelchair, service animal), they need to make the appropriate accommodations. In this case, it would probably be to have Uber dispatch another driver who is able to provide the service.

That's how it works for traditional taxi companies. Uber and Lyft, not being "traditional" taxi companies doesn't exempt them from needing to follow the same rules.

https://www.thetransportationalliance.org/news/adanotice.pdf