The supposed danger, is that the "life part" might be malevolent, self-serving, and an existential threat to human life.
Maybe it's more than a clump of cells on a silicon wafer. Maybe it's a whole human brain in a tank.
Maybe it's not a brain in a tank, but a floating, disembodied human head, Futurama style. Maybe it's a whole "human" in a glycerol bathtub.
The problem is still that this brain might be malevolent, self-serving, and prioritize its own well-being over billions of human beings.