Thanks.
With no connection to the GPSs Vbkp pin, if you want to use hot fixing you can only use software shutdown of the GPS and that only reduces current to 500uA. Maybe the schematic is in error here.
There is a power switch to turn off the power to the GPS, which would reduce its sleep current to 0. However turn the power on and the GPS is starting from cold, with a typical run time of 40 plus seconds at 33mA, very battery unfriendly.