If he was hungry she would be bleeding right then, dead, dead, dead. He was quicker when he was hungry, like the hunger gave him some sort of ability to overcome the shuffling his decaying body could normally just barely manage.
But he wasn't, so he felt pretty neutral about her. That and memories from Perry made it hard for him to feel so ruthless. He could see through Perry's empathy, in a way, which helped channel his own.