I think the game plan here was simply to provide a way to lock the player when it's sitting in the passenger footwell, rather than in the sled.

However, ISTR that somebody on this board hacked on their mk1 to add a laptop locking hole to it, and then added a solenoid to the sled, so that it was locked whenever the ignition was off.

Of course, I might have dreamt this. Even so, it's still a good idea.