Before revision:  Using a simulation experiment, I show that their MUE procedure generates excessively large estimates of \lambda _{z} when applied to data simulated from a model where the true \lambda _{z} is equal to zero.
After revision:  Using a simulation experiment, I show that their procedure generates excessively large estimates of \lambda _{z} when applied to data simulated from a model where the true \lambda _{z} is equal to zero.