It wouldn't need to take seven hours just to explain why Starfleet didn't do anything when two ships were combating on their front lawn, especially when it became clear both the Enterprise and Vengeance had become crippled to the point of being pulled into the Earth's atmosphere.
"Don't bother, Marcus obviously has everything under control. We'll just see how things play out."
*Vengeance crashes into San Fransisco*
I think a simple "I informed Starfleet that you're a terrorist that needs to be taken out for blah blah blah" would have sufficed. Quick, simple, informative and puts aside any questions for those who are taken aback by the events. Heck, at least that would have been something. Resorting to "it's just common sense" comes off like saying "no no, there's nothing wrong with the film, there's something wrong with YOU for not figuring it out." I do agree with the sentiment of not wanting to be spoon fed every information, but that doesn't seem to apply here since there's little info to go by beyond "he's a top admiral, look over there, a rabbit!". Go ahead and buy what hacks like Orci, Kurtzman and Lindelof sell, I'm not.
Then I guess every Trek writer that employed the same trope is a hack?
I think a simple "I informed Starfleet that you're a terrorist that needs to be taken out for blah blah blah" would have sufficed.
But he does explain exactly his reasoning for destroying the Enterprise. Does it really take that huge of a leap to think that he was already in contact with Starfleet?
The writing of the film suffers in two areas for me: the transition from John Harrison to Khan and the explanation for the torpedoes is really rough and both could've used more time in the writers' room.
Yeah, he's pretty formal and sounds on the record when he gives that order.
John Harrison: I wouldn't have made him Khan. But, I don't know what the word from on high was in regards to what and who had to be in the movie storywise.
Torpedoes: I would have kept the torps, but taken out Khan's people and loaded them onto the Vengeance in cryo, with Marcus using them as a human shield in case Khan got loose. Same disclaimer as above: If I had to have Khan, I would have moved the reveal to when he's captured the Vengance.