Why did the Prophet (peace be upon him) not punish that merchant who tried to cheat, and can this Hadith be considered evidence against the legitimacy of punishing a cheating merchant?

The Prophet, peace and blessings be upon him, sufficed with a verbal warning to the deceiver, either due to his ignorance or to prevent a repeat of his action, thus achieving the intended purpose of removing the deception. The punishment for a deceiver is legislated, especially if the act is repeated by him, and it is entrusted to the Imam to impose what he deems appropriate, such as Umar's pouring out of adulterated milk, or beating, imprisonment, and expulsion from the market, or selling the deceptive merchandise with a clear disclosure of the deception and donating its price as charity.