the OP said the person falsely claimed to the restaurant that it was inedible
Was that the story, you are correct, that might change things. However, the restaurant would understand what they meant by inedible- not that it was truly impossible to eat.
But, since you apparently missed the OP, I will copy it here:
Recently overheard in an office environment; two people ordered food from a dairy establishment, thereupon decided the food tasted terrible,called up to complain how bad the food was, they were throwing it out, however, they actually continued eating, received the credit toward a future purchase, full value, no food was left at the end. Derech agav a brocho achrono was made, after all how can one eat without benching!
What is the halacha?
It says “terrible,” not “inedible.”