Be nice to see April but heads with Kirk because he feels Kirk doesn't deserve command of the Enterprise yet or something.
Perhaps April was intended to be the first CO of the
Enterprise but had been off-planet at the time of the film. In his absence Pike took command during the emergency, then following the events of the film Starfleet promoted Kirk to Captain and CO of the
Enterprise, leaving April high and dry. He could be the CO of a lesser vessel, or perhaps manning a desk whilst waiting for another Constitution-class vessel to be constructed, or in command of such a vessel.