If I understood this correctly the ECU will not turn on the gas pump if someone uses "blank key' or hotwires the car.
If this is the only thing the ECU does, then the immobilizer is complete bull, because the gas pump cut off feature is easy to bypass with pliers ( to yank the relay out) and appropriate jumper.
This will make pump running as long as ignition is on but who cares.

I am REALLY hoping that the ecu also turns off fuel injectors, but I afraid it is not the case.
anyways I am using mechanical disconnect on starter circuit which will add some protection .

 

No matter what you do, if someone really wants your car badly enough they'll get it. Since our car has the immobilizer it would have to be towed. Steering wheel devices can be sawed through. No one pays attention to car alarms anymore. If they go thrugh all the trouble to get your car, they probably won't mind taking a few hours back at the chop shop (assuming they're not putting it on a truck to Mexico or chopping it for parts) to find the secret switches thay are installed to cut power to this or that.

 

This is an extreme case of professional car theft ring. I am talking about someone stealing car for fun or someone who is trying to find some relatively expensive parts (airbag, cat converter, EPS computer, etc.) to fix own or family member's car. Such thiefs are working alone and stealing cars let say once in few years (this is while they never getting caught).