Why pursuing the freedom promoting policy makes sense (among other foreign policies) even if one lives of the subjugation of others:
Freedom as a tool of conquest
“Please observe the conduct of the Romans. After the defeat of Antiochus, they were masters of Africa, Asia, and Greece with scarcely any cities of their own there. It seemed that they conquered only to give. But so thoroughly did they remain the masters that when they made war on some prince, they overwhelmed him, so to speak, with the weight of the whole world.
The time had not yet come to take over the conquered countries. If they had kept the cities captured from Philip, they would have opened the eyes of the Greeks. If, after the Second Punic War or the war with Antiochus, they had taken lands in Africa or Asia, they would have been unable to preserve conquests established on so slight a foundation.
It was necessary to wait until all nations were accustomed to obeying as free states and allies before commanding them as subjects, and until they disappeared little by little into the Roman republic.
Look at the treaty they made with the Latins after the victory of Lake Regillus. It was one of the main foundations of their power. Not a single word is found there that might arouse suspicions of empire.
It was a slow way of conquering. They vanquished a people and were content to weaken it. They imposed conditions on it which undermined it insensibly. If it revolted, it was reduced still further, and it became a subject people without anyone being able to say when its subjection began.”
Montesquieu, Considerations on the Causes of the Greatness of the Romans and their Decline, 1734 (CHAPTER VI. THE CONDUCT THE ROMANS PURSUED TO SUBJUGATE ALL PEOPLES)