In the 2009 Star Trek, Capt Pike field promotes Spock to captain and Kirk to first officer.
Why would Pike do this when only 5 minutes earlier Kirk was being yelled at for being on the ship at all?
Kirk wasn't even an active cadet because of the accusations of cheating, so he wouldn't even be eligible to serve on a ship let alone command one.
It goes back to what Captain Pike said to Kirk when he first met him. He said that Kirk had a tendency to jump first and ask questions later and he felt Starfleet had lost that ability and was becoming so cautious and risk averse and that it was not healthy. (Or at least he implied most of that with only a sentence or two.)
Kirk was the one who had gone with his gut, after putting all the facts together, and had come up with a conclusion even Spock (who was against Kirk at that point) agreed was good logic. And when Kirk had come to that conclusion, he was willing to jump in and take whatever risks he had to so he could bring the point to Pike's attention.
That he was on the Enterprise when he shouldn't have been and even made it on to the bridge when he should have been caught and put in the brig -- and then, on top of that, had come up with a correct evaluation of the situation when nobody else had put the facts together, proved Pike's point: Kirk followed his gut (which was always a big part of his character), jumped first, then worried about the questions. That validated not only Pike's view of Kirk, but since no one else had put the data together to get the same conclusion, also validated his view of what was missing from Starfleet.
My understanding is that he did so because there was no one else. He had a ship manned by cadets, and not a lot of spare crew members. Everyone was already busy with the job that they were meant to be doing, except for Kirk. And then aside from that, Pike is Kirk's mentor to some extent, or at least his sponsor - he believes that Kirk can be a hero, and in an emergency situation like the one they were facing, he'd want to put the most capable people available into a position to succeed, regardless of what regulations state.
Amiral Pike knew he was going into a situation in which he may not return. Because of that he wanted to make sure that the Enterprise and it's crew were well taken care of. He knew that Kirk had the ability to handle the position and felt that by putting him under Spock as Spock I believe was a LT Commander at the time, together they would be able to put their strengths together and accomplish the mission they needed to handle. Especially knowing that Spock's planet was in danger he would need to have someone with Kirk's ability to deal with stressful situations and keep an eye on what needs to be done. Sometimes logic isn't enough. As far as the suspension goes, Pike was an Admiral and more than likely had the power to appoint whoever he wanted as his first officer. Especially in times of war. I had mentioned in another post about this type of promotion, this possibly falls under a battlefield promotion where the rules are less strict when it comes to promotions and appointments and in many cases done out of necessity. Although this is a movie, General Eisenhower is an excellent example of battlefield promotions and how fast someone can get promoted. He was a Colonel in 1941 and by 1944 he was the 5 star General of the Army! The highest ranking member of the US Army as there is only one 5 star general in any service. Hope this helps some
