I'm pretty sure they have an anti-theft lock on the wheel when it's in park and off, like every car built after the late 90's, so I wouldn't waste my time trying that. I've driven cars without power steering, and my Hemi Charger for a while (classic Mopar quality) had no power steering and I had fatter tires with far more weight over the front tires than my SR+ does. It's not that awful driving without power steering, and I highly doubt the average person is incapable of it, it's just not gonna be something you do with a few fingers. Does it take more energy than turning a power steering wheel at a stop? Sure, but when you're rolling it's barely different.
Also, more importantly, I have never seen a report of the car trying to wrest steering away from a user. If that cropped up, I'm sure the media would be all over it to tell us what death traps we are driving. Same goes for if the car tried to accelerate during a braking action. I'm sure those systems all have double or triple redundancy built in to prevent just that. Same with how on ICE vehicles I never had the cruise control just engage and try to drive me into a wall, even if I'm pressing the brake. Could it happen? Sure, but it's very unlikely. Autopilot is dangerous, but when it's turned off the car is completely safe and will listen to your input, unless you're about to cause a crash, in which case it may brake. Anyhow, use beta software with caution when your life is on the line, that's my 2 cents. Hopefully the OP can get the service center to take him seriously, but we all know that it's like herding cats with them.