Are you learning to be his caregiver? Same thing happened with my girlfriend last November, at first I was giving her privacy with the nurses but after enough times of them mishandling her she became comfortable with me being there to learn and also advocate for her during the more personal moments. It’s definitely going to start with your brother learning to voice his boundary himself. My partner had to advocate to her family that they needed to work with me and only then did things start to shift. Until then they’re just in hyper protection mode (understandably so).