Unless there's a hardware component (say a physical key you need to insert into a slot on the side of the phone)
....
What about having to physically enter a passcode on the device's keypad? The locking itself can be in software, but that locking software can easily be hardcoded onto the silicon, and not something you can bypass with any software technique.
I'm sure competent hackers will immediately find ways around this stupid "Kill Switch" idea.
I would assume that reversal requires physical access to the phone, and also the manual entry of the correct password into the device itself, the password being one that is created by the user (initially randomized at manufacture, the default code for it being on a small slip of paper that comes with the phone when you buy it brand new). Since each password attempt would have to be manually entered, there is no viable way to expedite cracking such a phone, and I would imagine that most people even trying to do so would probably quickly abandon the attempt. And if the point of the law is to simply make theft of cell phones unprofitable, I think it would probably succeed.
I would draw the line at anyone who plays games frequently enough that they can personally identify with a subculture in society that plays the same games they do,.
So that would include Candy Crush.
It can also include people who play Monopoly, Football, or Mahjong.
"With threats of executing an official search warrant and taking the matter to court...an agreement was quickly reached to close down the site"
Really, if he really wasn't doing anything illegal in the first place, I can't see any reason he should have caved in on this... and this is in the UK, where it's my understanding that if you try to bring someone to court and lose, then you have to pay their costs, which I imagine exists to discourage overly subjective, baseless, or slapp-like lawsuits.
The fact that he yielded on this suggests to me that he was aware that a search warrant would find something on his computer(s) that shouldn't have been there in the first place. It's unfortunate the site is gone, but we're not actually seeing the whole story here. Sadly, because of how things have already went, we probably never will.
Make sure your code does nothing gracefully.