The pendulum rocket fallacy refers to the placement of the engine itself, not center of mass. Mass distribution absolutely matters, because with vectored thrust

The pendulum rocket fallacy refers to the placement of the engine itself, not center of mass. Mass distribution absolutely matters, because with vectored thrust, your engine can exert a higher torque on the rocket if the center of mass is farther away. You can try it yourself with a long pole and weight (e.g. broom with big brush?). Balancing the pole with the weight on top is easier than with the weight on the bottom.