Well. Yes your right I should probably use a quenching diode. But the way mine is wired is that the relay only energizes if the car is in gear. The ebrake has to be up. If the car is not in gear the ground from the ebrake goes through the relay to the NSS of the DEI alarm. If the car is in gear the relay is energized and the ground is disconnected from alarm. If teh e brake is not up it will not start also.
Everyone should use the NNS wire and hook it up to the ebrake for added safety. In the early 90's we did remotestarts on manuals using pins switches, reed switches and magnetic switches. I once started my car in gear and it went a lil ways even with the ebrake up.