What is the ruling on one who calls for the re-establishment of the Fatimid Caliphate and says that it is the state of Islam that holds the appropriate solutions for the present and the past?

The Ubaydid state, also known as the Fatimid state, was founded in Tunisia and then moved to Egypt. It claimed noble lineage, but scholars and historians, such as Al-Dhahabi and Ibn Taymiyyah, denied their Fatimid descent. Their rule was characterized by the spread of disbelief and heresy, the persecution of the Sunnis, and cooperation with infidels against Muslims. Among their most prominent beliefs and actions were: claiming divinity and knowledge of the unseen, demanding prostration to them, cursing the Companions, and killing scholars. Scholars unanimously agreed that the condition of Banu Ubayd was that of apostates and heretics, and that the outward manifestation of their doctrine was rejection (of the Sunnah (definition)), while its inward reality was pure disbelief.