Of course not. He’s not acting as a merchant when he orders pizza from himself on Doordash and can’t be bound by contract terms he never agreed to. Doordash didn’t ask him to sell pizzas on doordash, they decide to list his products themselves below cost. He doesn’t have an agreement with them except as anyone else ordering food from doordash, or doordash ordering food from him as anyone else could. Doordash doesn’t bind him contractually any way here.