Well those people can already buy free-range chickens. This is preventing people who'd rather pay less for cruelly-treated chickens from making that choice.
Given that it's a democratically elected government that made the regulation I don't think there is anything the "people who'd rather pay less for cruelly-treated chickens" can do here other than try to lobby for the rule to be reverted or moving somewhere where animals can be treated "cruelly" without repercussions. It's not always only a question of free market.
