Or maybe the writers just figured that 90% of the movie's viewing audience wouldn't really give a shit what Nero was doing, since it had no relevance to the story being told
I doubt that since the scenes in question were written, planned out, designed, budgeted, built, shot and edited to coincide with the script that at this point considered Nero's absence relevant. So with that being said, the writers (who I am giving way too much credit here) did in fact gave a sh** what the audiences thought. By the end of the day, it was JJ Abrams who made the choice to cut the Klingon scenes out.