That's very in character for her you know. This is the girl who was happy with holding Naruto's hands next to Neji's corpse. This is the girl who left her teammates to defend themselves when she saw that Naruto was in danger(although he already had Sakura healing him)
Do you honestly think she will stop knitting Naruto's scarf just because her sister is kidnapped?
It's so sad that you're right. They are trying to make this side character more relevant, but she has no personality outside of Naruto-kun, so the have to copy and paste other characters personalities on her, while other dynamic characters are forced to regress and be her little cheerleaders.