Not really.

First if You make it Ratiometric you loose most of the calibration Error. Your Bias resistor is the main error component. You do not have to provided power. Your signal is not near Vcc or Ground. It works pretty good.
Second He needs < 1C relitive accuracy. He is charging Batteries. His thermal drop to the case and the thermal lag (the heat has to work its way out of the cells) will be worse than 1C. The Delta Temperature is important. The max and min will not be as important. The battery will not be that bad off at -21 as opposed to -20.

It works on all my battery chargers.