It's not that Pitou fears disobeying the Kings orders. It's that she wants to honor what the King, and important person to her, asked of her. That is a huge, huge difference and is a nice indicator of the burgeoning humanity the ants are experiencing. Of course, to Gon, it is extremely unfair that this Ant, that "hurt" Kite and played with him like a toy, is actually trying to defend someone. Hence the overwhelming feeling of anger and frustration.