Well, like a good synopsis, it raises more questions that it gives answers.
"...an unstoppable force from within their own organization...."
If it's someone from inside Starfleet, it will take one hell of a backstory for it to be Khan. Despite a murky past, a quick background check by Spock in "Space Seed" was enough to know Khan was dangerous. Do former despots from the past get admitted to Starfleet Academy as a rule?
"...detontated the fleet and everything it stands for...."
Well the fleet and what it stands for except for the Enterprise, apparently.
"With a personal score to settle...."
Kirk's mother and brother get killed? Or, maybe Pike, the closest thing Kirk has to a mentor and father figure, buys it in the first nine minutes trying to defend against the unstoppable force. Or maybe the score is to be settled with someone who turned his brother into the force. "[S]acrifices must be made for the only family Kirk has left..."
because he had to defeat his brother the same way TOS Kirk realized he had to defeat Mitchell.
"...a war zone world...."
An on-going conflict further ignited (or, detonated) by the unstoppable force, or a new one created by the unstoppable force? A local war or an interplanetary one? A last stand or a jumping-off point?
"...a one man weapon of mass destruction."
One-man because of his leadership over well-armed blindly devoted followers that do whatever he asks quickly and without question, or because he has enhanced powers of some kind and is acting alone?
Is he rational? Crazed? Tragically or unwillingly became the terror?
What is his motivation? Conquest? Revenge? Random terror? Revolution?
Also, if he is a one-man weapon of mass destruction who was able to disable the entire fleet, then why can't he crush the Enteprise like a bug when he comes across it? Does he have a motivation not to?
When does all this take place? Not long after Nero was defeated? The full four years? What is the general state of the Federation at this moment? Is it vulnerable given it lost Vulcan and a good chunk of the fleet was already destroyed by Nero? Don't forget the 47 Klingon ships Nero destroyed, too. Is there a power vacuum someone is trying to exploit at this weak moment in the Alpha Quadrant?
So many questions. Still no answers.
Hell, perhaps it's Robert April, and he's pissed about the canon debate over him all these decades. Maybe when they chose to make Pike the first captain of the Enterprise in this universe, it was just too much for him to handle. "That was my chance! That ship should've been mine! I could've been official canon. I could've been somebody, instead of a cartoon, which is what I am, let's face it."
Seriously, we're speculating about charcters who became villains in TOS. Why couldn't Cumberbatch be someone who was a "good guy" in TOS who goes bad in this movie? Someone even speculated it could be Kirk's brother. Why not? That certainly trumps best-friend Mitchell as a tragic figure and foil for Kirk. And, while we know Kirk emerged from a bad childhood with his fate restored, what happened to his brother?