Tis true...
Turbo timers are not always necessary if you allow the car to idle for a minute or so before switching off. When I still had the Clifford alarm the car was set to idle for 60 secs (or whatever you wanted) after the key was pulled out. This meant that I could also lock the car while it still idled and walk away.
With my current turbo timer, unfortunately I have to sit it out (the idling) before I can lock the door and arm the system. Damage to the turbo can be caused if they are not allowed to 'cool' down first. Somebody more technical could give you the precise details as to how the turbos can 'cook' themselves if left to stand whilst hot. I don't know the actual mechanics of it - just been told that damage will occur.
Y.