I think in order for it to work, it needs to see valid communication and then lose that communication. That's why power has to be on before shorting the network. If it is open, it just waits to see if the network is fixed and whatever it does to disable the no-start logic never happens.
Which brings up a point. You might need to have a CTM on the network before it will see a good network. On the later cars with CAN bus, there are 2 master nodes that form the start and end. If one is missing, the network doesn't work. Not all cars/networks are the same, but it sticks in my head that the CTM and PCM are all that is needed to make the CCD bus work. Not sure on the PCI bus networks though.
I had planned to install a CTM on my build and enable/disable VTSS using a fob. This would have given me a measure of security against hotwiring the car. An extension of the project would have been to wire the existing door switches into it and hooking it up to a horn and headlight relay so it could sound an alarm when a door was opened while the system was enabled. The last step would be to wire power door locks to the CTM as it is setup to unlock the doors through the same fob.
The nice thing about incorporating the CTM is then it shouldn't matter if the PCM is VTSS enabled or not.