Ok so the reason he hates, sakura is the cause how she's not worthy of being a ninja.

He hates,her cause she's a weakling and is always focused on sasuke and doesn't focus on Training.

so he simply Doesn't care what she does as he's learned naruko can take a hit.

so Frostbite will simply see her power level as a weak level and,her level of fighting is pathetic as there is more powerful ninja who can kill her with just their skills and, power in genjutsu and, taijutsu.

so Frostbite will not hate her if she truly earns his respect.