Kingsley was smart as a fighter. He didn't generally rush into battles or encounters likely to turn violent. In general, with his life, everything was done in detail with careful planning, like the ordered way he kept and cleaned the flat. So there was a much greater chance he would have lived. But Kingsley didn't like to focus on the negative when fighting. It was easy to hate Voldemort and everything he stood for, but that kind of strong emotion tore him apart, in a bad way.
The talk about her working for moving again hurt, but it wasn't until she spoke about wanting revenge that Kingsley mildly regretted his words. The negative emotions were there. Kingsley felt them strongly. But they didn't get to control him, to drive him.
"Hate is easier to feel than love, than sadness, than a million other emotions," Kingsley commented, "It burns. But it also burns you." And he was so concerned for her. While yes it was a step toward feeling, over apathy, Kingsley was concerned for her.