However, his father, Al-Hasan, feared for his life from the tyrant Abbasids, and thus, his son was sent to Madinah and was hidden away.
He still remains hidden today.
Ja'afar bin Ali Al-Zakee, the uncle of the "Mahdi", also denied that his brother, Al-Hassan, had a son.
Shias refer to him as "Ja'afar the Liar" due to this.
Kamal Al-Deen 1/470
The financial motivates behind this claim are evident.
She narrates witnessing a miraculous scene when the mother of the "Mahdi" Sawsan gave birth to her son.
Al-Ghaybah lil Tusi 236
Al-Ghaybah 238
In another report, Hakeema indicates that she never met the "Mahdi".
Al-Ghaybah 230
After all, the earliest biographers didn't include a "Hakeema" when listing the progeny of the 9th Imam.
Qamus Al-Rijal 12/238
Regardless, more research is required in regards to the origins, motivations, and details that surround Mohammad bin Al-Hassan.