The reason for shelving the post-ST2009 novels is that the filmmakers wanted to reserve for themselves the right to move the story forward, but they're okay with tie-ins set before the movie, like IDW's Countdown, Spock: Reflections, and Nero and Pocket's YA Starfleet Academy series. So there's no reason to think a Kelvin book would be off-limits, at least not based on the shelving of the four sequel books.
Why?
They want to respect Trek book canon?
We only have speculation, but it's more likely the other way around. Never forget, the tie-ins are a very small tail on the very large dog of the film/TV franchise. The job of tie-ins is to follow the lead of the canon, not vice-versa. (There's no such thing as "book canon" here. Canon means the core work, as distinct from derivative works.) It could be that the filmmakers want to make sure there aren't any books or comics published that end up contradicting what happens in their later movies.
Again, though, I'm in no position to do anything more than repeat what little has been announced to or speculated by the public. If you want to know the reasons why, you'd have to ask the people in charge of the franchise and its licensing. And if they don't care to make their reasons known, that's their prerogative too. They're the ones making Star Trek now, and the tie-ins exist to support and supplement their efforts, so they get to decide the parameters of the tie-in line.