Shia shaykh and known writer, Baqir Sharif Qurashi in his book “Life of Imam al-Mahdi”, (Publisher: Ansariyan Publications – Qum First Edition 1427 -2006 – 1385) at the page 241-242 wrote:
In the tradition of Zurarah this same cause is mentioned by the Imam that: “For the Qaim (a.t.f.s), there is an occultation before his reappearance.” Zurarah immediately asked, “What fora” Imam replied, “For fear of being murdered.” Shaykh Tusi says: The cause of the obstacle in the reappearance of Imam Mahdi (a.s) is nothing but the fear of being killed. Because if there had been any other reason, his remaining in occultation would not have been justified. [Ghaybah, Shaykh Tusi p 199]
So let us check together history.
The Fatimid Caliphate or al-Fātimiyyūn Shi’a caliphate first centered in Tunisia and later in Egypt that ruled over varying areas of the Maghreb, Sicily, Malta,the Levant, and Hijaz from 5 January 909 to 1171. That’s mean they ruled 262 years! No doubt that shia Mahdi would be most welcomed quest in that shia caliphate during these years. But, he didn’t appear.
The Safavids ruled Iran and around countries from 1501 till 1736. 235 years of powerful shia ruling. But 12-th imam still didn’t appear.
Modern Iranian shia state. Since 1979. 31 years. Still we haven’t seen shia Mahdi coming from occultation.
As we seen Toose said that reason of his going into the ghayba: is nothing but the fear of being killed. Does that fear still exist?