Why is everyone assuming the author intended to waste the food? You're assuming a malicious actor, when instead they were at best a foolish one. They ordered more food than they could eat. They didn't order food with the intent to destroy it or harm the business.

Having an all you can eat promo guarantees customers will not behave perfectly because the normal routine of ordering and eating being paired to price and consumption is discarded (flat price).

If the business is worried about spiralling food waste they should reconsider the promo as it is inherently wasteful compared to other dining standards. If they want to keep the promo they should pace delivery of food to anticipate customer behavior.

Suggesting an ignorant / mistaken customer is a "bitch" who needs to be "slapped into next week" is yikes.