How to accurately measure electric motor torque?
You are mistaken.


The torque controls the current.


Not vice versa.

That maximum torque your servo is specified at is the maximum you may apply without damaging it. This is most likely due to the limitations of the gearbox, because electrical motors are extremely forgiving. If you overload them, the only thing happening in first place is overheating, which is okay if you give the motor a rest to cool down afterwards. But the gears inside the gearbox may break mechanically if you apply too much torque, and they fail in an instant.

What you should not do is stalling a DC motor completely however, because the high current can damage the commutator surfaces if it's not moved.