I speculate that CL represents personal freedom and individuality, as opposed to the collectivism of the NCR. How do slavers represent personal freedom you ask? It's not that complicated. The Legion represents personal ambition unencumbered by things such as laws, morals, or ethics. The Legion will tell you that the strong prey upon the weak. That's part of nature and can't be disputed. Strength is a personal choice. People either choose to be strong or they choose to be weak. The weak know that they strong will inevitably dominate them, and yet they choose to be weak anyway. You don't ant to be dominated by another? All you have to do is choose not to be weak and to be strong. In order to be strong one has to look at the world and determine the nature of strength and weakness and what it takes to be strong. The strong person does not make judgments concerning what is necessary to become strong. The nature of the world determines what is necessary and if you want to be strong you adapt accordingly.
That's what the Legion does. They see the wasteland for what it truly is, not what it could be or should be. They see what is necessary to become master of it. The poor fools whom they capture as slaves knew the risks of being weaklings and chose to be weaklings regardless. If you aren't strong enough to protect your own life and freedom then you don't deserve it. If a person is strong enough to take your life or freedom from you he's more deserving of it. The Legion allows people to reach their highest potential without having idiots and weaklings hold you back.
I think it's closer to the Fascist collectivism of Mussolini, where the thugs in power subjugate and oppress others into obeying the will of the Caesar. They deny personal freedom and individuality to anyone not physically strong enough to take it by brute force. Even if you're physically strong, you'll only be kept alive as long as you don't question those above you. That sounds more like chains, than freedom, to me.
I don't know how well the New Californian Republic protects individual rights, but it's a fair bet that they do so to a far greater extent than the thugs of the Legion. I think it's very likely that individualists will take the
individualist approach though, by not joining either faction.