Why is Muawiyah ibn Abi Sufyan, may Allah be pleased with them both, not called a Rightly Guided Caliph?

Mu'awiyah ibn Abi Sufyan was a great Companion and a scribe for the Messenger of Allah, peace and blessings be upon him. His rule was characterized by mercy and benefit for the Muslims, and he undertook conquests and jihad in the path of Allah. The reason he is not considered one of the Rightly Guided Caliphs is that his caliphate came after the thirty years specified by the Prophet, peace and blessings be upon him, for the Caliphate, as stated in the hadith: "The Caliphate in my Ummah will last for thirty years; then there will be kingship after that."