Katie continued to cry without knowing that Merah had opened her eyes and looked at her sadly. The truth is, Kinsey was no longer angry. If the situation were reversed, Kinsey would do the same.
Kinsey would not care about his own life and would unquestionably save the people he cares about.
He had failed to save his mother, and he couldn't even protect Catherine even though he had placed an eye on his sister. Because of that, he would not think again to save the people he loves, even if he has to sacrifice his life.
It's just... he still couldn't help but be angry at Katie's carelessness. Judging by the situation, the wounded of Oostven warriors were formidable warriors. They won't just die from getting injured.
Likewise with Merah. The red wolf only needed to rest for a full week for the wound to heal. Katie didn't need to summon rain and infuse her life energy into the rainwater.