Non-disabled passengers may sit in courtesy seats if they are empty. If a non-disabled passenger is using a courtesy seat when a passenger with a disability boards a vehicle and needs to use the seat, the non-disabled passenger should offer the seat to the passenger with the disability. Signage should alert all passengers to this system. However, some passengers with disabilities may prefer not to use a courtesy seat. They may be able to sit or stand elsewhere in the vehicle. Each passenger with a disability will know whether or not a courtesy seat is useful for them.

Read more at
https://aoda.ca/courtesy-seating-for-passengers-with-disabilities/