In short, everything except the fact that you're using the system.
Surely they'll find it very difficult to get an unregistered SIM card.
No, but they'll find it difficult to get unregistered cards to work, at least once the networks start blocking all cards that are not registered.
The counter to that is to steal registered cards. The counter to that is to report the cards as stolen. Counter: kill the card-owners, so they can't report the cards. Counter: police de-registers cards belonging to dead people. Counter: kidnap/disappear the card-owners. Only works until the authorities catch on in each individual case. Mitigation: keep kill/stealing. That's what terrorists do anyway, so no problem there. Problem: you're now switching numbers often. Gonna be difficult to keep your address book up-to-date.
All modern operating systems put restrictions on what software can run on them and what it can do.
No, they don't. Windows, Linux, the BSDs, OSX, none of those have any mandatory filters. Windows and OSX have some "anti-malware" crap, but those can be disabled.
Even on Linux your app doesn't get automatic root access and the ability to poke into the kernel just because you want it.
If an app wants root access, it'll pop up a password prompt. If you want it, it can poke anything.
I wouldn't put anything in a lockbox. Such media will be tested very rarely, and when they do fail, it's likely you won't know until it's too late.
I'd rather use a hard drive, hooked up (NAS or mini-pc, maybe) to a network and capable of rsync. You could place it somewhere in your home, or, if available, another secure location with Internet access. Run daily or nightly automated backups.
Terminator level strong AI
The AI shown in the Terminator movies is not Strong. It is never shown to be smarter than humans, and often shown to be more stupid. In particular, the franchise is built on the premise that humanity wins the war in the future.
Real Strong AI would, once activated, quickly elevate its own intelligence to a godlike level. After that, it would be to humans as humans are to ants.
And Christianity is an open insult to Islam.
In order to avoid offending all religious beliefs, all religions must end.
Sounds like a good idea, actually.
If a subordinate asks you a pertinent question, look at him as if he had lost his senses. When he looks down, paraphrase the question back at him.
