AFAIK, he hasn't graduated yet. And even so, who have we ever seen graduate as a Lieutenant?
was offered to graduate as a Lieutenant if I went into the real
U.S. Navy, and that was mainly for testing well on the ASVAB. So I'm thinking it isn't that far-fetched.
Entertainment Weekly Magazine wrote:
"Black is apparently the color of space cadets in Abrams' universe"
Some here seem to be hanging an awful lot off of this, but Entertainment Weekly isn't a fanzine, it's meant for general consumption. For all we know, they meant "space cadet" as in "get yet head out of the clouds, space cadet", and not as in any sort of actual rank. Seems a lot more likely to me, in fact, since Starfleet cadets are "cadets", and not "space cadets".
Could it be that the black outfit is some sort of more temperature regulated uniform for hostile environments, like the cold area he is shown in in one scene in the trailer?