I think maybe the lever arm release is what he can't undo.
At first it stumped me but then I recalled seeing some bikes with the main cable so tight and finely adjusted that it did not allow enough travel to disengage the lever arm. It would create a off/on braking action rather than a graduated one.

Also, OP. If you don't have fenders consider some sort of guard like I have front and rear on this bike between the straddle cables and tires. Otherwise a cable failure will allow the straddle cable to drop onto the tire and you will stop REAL quick!