Maybe it was because of who he was, what he was, the powers stored up in his body, Jesse wouldn't have been able to say had he cared. But it worked through his system quickly. The bite happened, he heard Zoe coming - too late, too late - and then it overcame him.
His body died in spectacular fashion. Faster than even Buffy had started. He was dead and gone in seconds, ready to take his turn in devouring others. He was aware of his surroundings, the familiar scents of those near him. He was aware of the fact that Buffy was dying and her meat was no longer worth anything to him. No longer good. Not really meat.
And he was aware that Zoe was coming, and that her meat was good still.
Jesse turned on the Amazon and lunged, his mouth open and ready to bite, aiming at the arm holding the weapon, it was closest. Extended out to him as if an invitation to feed.