: As for Palmer, she's mildly likeable in Campaign. She's actually witty and
: admires the Chief, nice qualities, likeable qualities. In SpOps, she kills
: it. They write her as a blanket military supremacist. She is the perfect
: Spartan IV in ONI's eyes. And that may lead to a whole new war, or the
: subjugation of every non-human species.

I think Palmer's character was still being ironed out via Early Installment Weirdness in Halo 4, and maybe still is. Also, Brian Reed acknowledged that Palmer has something coming:

Palmer’s a lot of fun to write because she’s half-way to a force of nature. She has a lot of “shoot first, ask questions later” in her bones, and so far in her life that has proven to be the best operating procedure. Of course the day will come that her style backfires and she realizes she needs to learn about something the rest of us call “subtlety.”