I feel it's fairly obvious Nero was quite deranged. When Pike tells him he's 'confused, he's misinformed' during the interrogation sequence, it's apparent that while Nero is in fact correct in (some) of his assertions, he also is off his rocker.
Just because there isn't a clear-cut path from his circumstances to his targets... really doesn't bother me. It's quite blatant Nero has lost his marbles and maintains only his cunning, and his crew follows him because they're all screwed-up in the head. Given their situation, it's a relative no-brainer as to how that happened.
Take into account a certain scene in the film; I don't really remember where or the gritty details, but Nero tells his subordinate they're going to 'kill everything' or something else fairly vindictive, and his subordinate gives this sick, twisted look that speaks volumes to me. They live to destroy.