Mr. Laser Beam wrote:
Look at the new Abrams timeline in the Trek franchise. In the Roddenberry and B&B eras a radically altered timeline would have been repaired by either our heroes to set things right or by time-traveling "temporal cops" from the future
No one in the 'prime' timeline knows that the Abrams timeline even exists. They have no idea where Spock Prime and Nero went. From their point of view, both men simply vanished. Can't repair a timeline that they don't know exists...
There's the theory that the unique qualities of the Red Matter black hole/singularity masked Nero's arrival in 2233 and the changes made to history so nobody from the distant future could detect the alterations with their temporal sensor equipment, but that's just more technobabble really. Who knows what the "real" in-universe explanation might be.
Maybe Braxton and Daniels were in the men's room when it happened and never took notice?