You've known Shinobu for longer than Kanae has been dead and longer than Kanao had lived with them. You watched her change as a person, you knew you couldn't stop her

When you saw her being so rude to Giyu even if it was teasing you knew Kanae wouldn't want that so you scolded her everyday for it. She would just do her own thing while listening to you scold her like a child

"It's just some teasing, I thought you'd know that by now. You don't need to scold me."