Good points, however, brake systems and steering systems, while having some level of power assist in most vehicles, is still largely mechanical. You still have mechanical steering that would still work and the brakes still have hydraulic fluid that would still push the pistons in the calipers even without power assist. It would require more physical strength to steer or brake, but both systems would work. Try turning your car off (safely, while driving slowly) in a parking lot and see for yourself.
And this technology probably wouldn't work on any vehicle that predates ECUs. So you get anything from the 1970's or earlier (maybe a few in the 80's) that couldn't be stopped. Savvy folk would probably decide to add some shielding to the ECUs, but whether that would work remains to be seen.
The article also states that they tested at 15mph. What happens when you're doing 95mph or more?
So now this technology is out there and it gets into the criminal's hands. Ostensibly, they could drop these out the window of their car and have it shutdown police cars. Or armored trucks.
Time for me to get an extra large tinfoil hat for my car.