I think I have said this many times. The clue lies in what the OP said.
Zarvan no offence is the problem. He is Mr Average. They wear their religion on their sleeve. They regard the self appointed custodians of Islam as viceregents of Allah on earth. This means in cause of their blind faith they will be ready to die and destroy Pakistan. Between the Pakistani state and the self appointed custodians of Islam they will support the custodians like Rizvi.
Where am I ging with this. iIf the state ever used iron fist against the self appointed custodians of Islam their supporters[implicit or complicit] would join in as they would regard it as attack against Islam and they would think of themselves as warriors of Allah against the corrupt America/Jew stooge of a Pakistani state. When pushed hard the army migt dissolve or fall apart on the stress imposed on the soldiers of choosing between Allah and their officers.
Many might suggest the example of the war against TTP to disprove my theory. However despite few cases of desertion the army remained cohesive and after the APS attack it rallied around for fight to death against TTP. But people must keep in mind the TTP was predominantly restricted to the tribals areas of FATA and the army is not recruited from that region. In other words the fighting took place on the margins of Pakistan against a fringe group [tribal Pashtuns].
However the prssent problem with TLP involves the core areas of Pakistan and instead of being restricted to margins it diffused across Pakistan. Peshawar, Islamabad, Gujranwala, Lahore, Karachi the core areas of the country were effected. Taking on the TLP here could lead to widespread insurection striking at the very core of the country and cause the army to dissolve when people like Zarvan would tout the soldiers to defect - knowing that the average soldier would be also from the very same group and could be Zarvan's brother. The Mr Average.
This could lead to slippery slope to civil war. And that is why the state backed off because people at acutely aware of this.