Iris was not sure what she wanted to achieve when she said those words to Cane. She did it in the heat of the moment, she wished for him to know how much his decision had disappointed her, but now when she thought about it again, Iris felt like she was so insensitive.
Of course, Cane cared so much about his people, though he didn't show it openly. She knew about it from the very beginning and her comment was so insensitive where she did not think about his feelings at all.
Iris stared outside of the window, feeling guilty, but she couldn't rest her conscience with the thought they were leaving.
It was not that Cane didn't help these people at all, he helped them by providing them basic things they needed to survive and even ordered Grace to heal them, or commanded his warriors to pull the dead bodies out and gather them in one place, so they could give their loved ones a proper burial.