remote start w/electronic parking brake

Possibly you could use a status output to control a relay that would always ground the parking brake wire when the car is shut off.  You would have to control the relay both with the status output (so whenever the status output turns on the relay switches the wiring back to normal) but also control it off the stock ignition wire so that whenever the key is in the "ON" position the wiring will be back to normal.

This would cause the parking brake wire to always read ground when the car is off and as soon as the vehicle is either started by the key or remote started the parking brake wire will go back to "normal" and therefore shut the vehicle off if the brake isn't actually active.  This assumes the system will shut off if the parking brake drops out right at start up.