That doesn't make much sense. If Gon had killed the defenseless Pitou, she would have taken a much more permanent sort of leave of absence from her king's side. Killua might have found it interesting that the king and a royal guard would be so desperate to save a human, but such a thing would be of nothing but academic interest unless the Hunters are planning to lose and the king is allowed to live. I could actually believe Killua making preliminary plans even for such an outcome, but I don't think that's what happened.