While I agree there will likely be remote disabling procedures for emergency/law enforcement reasons, I don't see where you get the "no cause" piece of your slippery slope. It seems it would be much easier to unjustly pull someone over with current human-operated cars; with automated cars, reasons such as "they were weaving" or other gray area justifications will no longer be available to LEOs.
Yes, there has to be a reason. Of course, it's very easy for an officer to say "He was weaving in traffic", or claiming you were speeding when you were not, or simply lie about you using a turn signal.
I'll bet most people have a story like that. Probably from when they were younger, but not necessarily. And that's not even getting into "driving while black" and the likes.