And that's very important: \ if there there truely is no harm in running a single tank through then the gas station could argue the expense the owner incurred was unnecessary and therefore they are not liable for any damages since there were none.
There doesn't have to be vehicle damage for there to be liability if the fuel was mislabeled because the consumer has the right to receive the product they paid for. Under our long-standing system of tort law, a station with mislabeled product is liable for expenses to return the car back into the expected condition, ie. full of gasoline, not less expensive alcohol. And the CX-5 manual does instruct that E85 is not an acceptable fuel.
Most station owners would understand this liability if they made such a mistake and would pay reasonable bills without the need to take them to court. This is especially true in states with strong consumer protection laws because, in cases this clear cut, the court can impose punitive damages in addition to the other parties legal fees for such unreasonable behavior. For the same reason, a consumer who negligently filled their gas tank with fuel that was clearly marked E85 would be foolish to take the station to court because punitive damages and legal fees could be awarded to the station owner.