
No, he's totally mistaken. Coming from a shia tradition, they hold the alternative perspective of imamate rather than caliphate. Islamic sunni scholarship has always had agreement and consensus on the ahkam of the caliphate - the Islamic form of governance.
This piece critiques Mehdi's stance on the subject in some detail:
It highlights evidences from all the Islamic sources of law on the caliphate and reviews what Muslim and non-Muslim scholars say on the issue and what those who currently think like Mehdi, the modernist thinkers both secular and non-secular, say and have said through their recent history.
It is pretty comprehensive.