When benzodiazepines are at play and someone is experiencing the brutal symptoms of what is commonly known as "tolerance withdrawal", the absolute last thing on earth you want to do is lower the plasma level of the benzo...lowering the plasma level of benzos when someone is already experiencing 'tolerance withdrawal' can & does induce seizures.
Almost 100% of the time an activated charcoal poultice on the liver is 100% safe and packed with goodness. In the case of certain drug withdrawals, it simply can't be used.
Once he's stabilized, he can choose from many options for cleansing, and there's quite a few herbs he CAN take (and cleanses he can do). But right now he's got to get stabilized so he can stop the continuous damage to his adrenals and GABA receptors.