Hatchback safety depends on the specific vehicle, its condition, the people using it, and how it is loaded. The rear hatch tells you about access, not how well the car will protect occupants in a crash. Crash-test evidence, suitable restraints, maintained tires and brakes, clear visibility, and secure cargo all deserve separate attention.
The shared passenger-and-luggage area makes loading especially relevant. A practical folding-seat arrangement can expose occupants to unsecured belongings if used carelessly. Evaluate the car's safety equipment and ratings, then use its cargo space within the limits and instructions for that exact model.