I'm not ignoring anything...in fact, I'm one of the few who are actually taking the movie in as a whole. Every argument I've seen in favor has been basically "well, the movie didn't show it...but we know Superman..." I am taking the movie as its own story...and the story is OBVIOUS.
The movie repeatedly, over and over and over again, pushes the idea that he is wanting to know who he really is, and wants to learn about his homeland. The movie NEVER MENTIONS that he has superior morals and would try hard not to kill. In fact, he does petty, angry, reckless things such as destroy that truck. In fact, the movie even shows that it migth be better to watch loved ones die rather than save them. In the end, he chooses to kill Zod. Given what we know exclusively from the film, with no input from other sources...the story is clear...Clark was mourning the death of his connections with his homeland.
I know I've said this a thousand times...but seriously...it is just as annoying seeing people say "Superman does not want to kill but was sad that he had to" when you really don't see that in the film itself.