Had my car stall on the highway once. Pretty scary because you lose power-brakes and power-steering as you're trying to pullover.
Was it a hacker? Nope, just a dumb mechanic that got trash deep into the air intake during a routine oil change.
How many (dumb mechanics)*(routine oil changes) are there in this country? Five-Six orders of magnitude more than auto hackers, which is why I don't see any harm in one more (where the driver knew ahead of time it was going to happen).
The difference is your 'dumb mechanic' made an unintentional mistake.
These people, on the other hand, knowingly and deliberately disabled a car on a highway. Yes, they had a plan, but they are still running their little experiment on other unwitting drivers on the highway. I don't consider the manner in which they ran their test to be ethical; it should have been performed on a closed track.
I will point out that the car didn't stall. Power brakes and power steering weren't affected. The transmission was forced into neutral which did affect his ability to accelerate. Still reckless and stupid. And probably worthy of a call to the police -- though debatable. I don't understand why they didn't just test this in the drive way or on jackstands or at a track or on a dyno. Driving the car on a public street was not needed.
Your recklessness is judged by the extra harm risked.
You can't just waive it away because other risk is more dangerous across the entire nation. Under that standard: One little murder is a rounding error compared to the 2.5 mil who die each year.
The fact that the driver knew ahead of time does mitigate the danger but does not excuse the remaining danger. The fact that there are already lots of dangerous stalls seems completely besides the point to me.
I think it's 100% OK to test on a private car on a private track.