I see...The 737 is quite different. If you shut down the engines with the APU available then the cockpit will go dark. It can even go VERY dark depending on the mod status of the aircraft, because to get full standby power on the ground you have to select the standby power switch => gnd (73 classic - prob not the NG in this case). There is no automatic take up of the load, the busses simply go unpowered.
The evaculation checklist prompts for all power units to be shut down including the APU. So by following SOP's the crew WILL loose VHF2 and there is nothing that can be done. I think that you will agree that given the electrical arcitecture on the 737 (different from your Hawker) then there is nothing to be gained from having the APU operating. This is why I suggested standby pwr for VHF2...