Honestly, I think people overestimate the value of Find My iPhone in a theft situation. Perhaps they have never had a phone stolen. Here's how it often goes...
My friend had her phone stolen at a party. We immediately logged her into iCloud on my phone to look for it on Find my iPhone. The phone did not appear, so we requested a notification to be sent to her husband's phone when it turned up.
Two weeks later, it finally did...in a Mexico City suburb.
What do you think the police are going to do with that information? At best - shrug their shoulders and say "Them's the breaks". At worst, literally laugh out loud at you for suggesting there's anything they can do about a stolen item that is in Mexico (or Russia, or any other country where stolen items often end up.)
Find my iPhone is a great feature when you've lost track of where your phone is physically. But it is not an effective anti-theft feature in most cases. If you are (un)lucky enough to have your phone stolen by some feckless meth-head who lives twelve blocks away, you might actually manage to get the cops to recover your phone from whatever pawn shop he sold it to when it pops up on Find My iPhone.
But most of the phone theft is being done by organized operations that know to turn the phone off and not turn it on again until it is in another country.
The article is correct: "Find My iPhone is a useful method of locating a lost device." It's important to note what is not being said there, because it is generally not a useful method of recovering a lost device.
Activation Lock is the real anti-theft feature, and it is unaffected by this particular exploit. But even that is not 100%.
Remember, security is usually a matter of deterrence, not all-out prevention. There are likely low-level jailbreak exploits that get the bad guys around the activation lock. And even without that, I'd be willing to bet they can disable the lock on a decent number of phones just by attempting the most common passwords (letmein, 123456, etc). And all of those they can't unlock can be easily bait-and-switched with a working phone to sell the expensive brick to an unsuspecting sucker. So even an activation-locked iPhone is worth stealing simply because it looks like an iPhone.
To sum up, the best actually-effective theft deterrent is physical control of your phone at all times. Couple that with getting rental or homeowner insurance that covers theft of personal effects, because if you get mugged physical control is not going to stop a bullet.
