He bought a car with the ability to blind oncoming drivers. This is illegal.
I bought computers with the ability to infringe copyright (which is illegal), make unauthorized connections to and/or deny service to other computer systems (which is illegal), utter forged instruments (which is illegal), and they can do a lot of other illegal things too.
The manufacturer fixed the car so it now meets regulations.
My computers' operating systems have evolved over the years to enforce various DRM, Windows in particular has some socket limitations by default, most image software and printer/scanner drivers use the eurion constellation so I can't scan and print $100 bills. I accepted these things by choice because I don't feel like they deprive me of any functionality that I would use.
If he still wants to blind oncoming drivers, there is a thing called "high beam" which he can use whenever he wants... just hope that it's not a highway patrol he's blinding.
In other words, even if he gets his car "upgraded" to disable a feature that he paid for, he can still do essentially the same thing? Why get the "upgrade" and remove a paid-for feature, then? As I mentioned and you reiterated, there are police to take care of unlawful operation of his vehicle's features.
Your computer analogy is stupid... how about a car analogy?
Heh. I bought a car with the ability to go 120MPH, and I know it will do at least 100MPH (erm, according to what the speedometer claims that is, of course I've never ever tested that personally...). That speed is not legal in any jurisdiction in the United States. Should it be okay if the next time I go in for an oil change, they install a governor that stops my car from going over 75? Fuck no, and if that became some sort of mandatory thing, I'd start changing my own oil.
"You might do something illegal with that!" is never a valid reason to take something away from someone.