Disclaimer: I do not own Naruto.
Kiba could never bring himself to hate Kabuto. Dislike the man with a passion, yes, but he would never be able to hate him.
It didn't matter that Kabuto betrayed the village. It didn't matter that he was a Sound spy. It didn't even matter that he was unwaveringly loyal to Orochimaru. Kiba would never be able to hate him.
Kiba knew he would be forever grateful to Kabuto. If Kabuto hadn't disguised himself as an ANBU for the Chunin finals, he would not have been there to heal Hinata, and she would have remained ill from the damage she received during her battle against Neji. Even though Kabuto was an enemy, he still healed her.
Hinata meant the world to Kiba. She was his most precious person. It was because of her that Kiba would never hate Kabuto, and that's all there is to it.