It's threatening for the simple reason that oppression is bad for the oppressed. It warps their souls, filling them with a bitterness and violence and hate which is not always directed at the oppressors. The duty to free the oppressed is threatening because it means living with them, and at best that can be a dangerous prospect. Moses knew that. People don't deserve freedom because they're good.
People deserve freedom because they're people.
Nevertheless, the danger is real. But as is increasingly clear, the world is dangerous whatever we do. We all experience the terrifying nature of the world, and we know it threatens us unjustly. And so we cannot escape that terror - we are, after all, Isaac's children. For while we must be Isaac's children, we can choose to become Moses' disciples.