The problem here is that egalitarianism is the ethos that opposed authoritarianism, rather than some hypothetical individualism/autonomous ethos. Further, it seems to be implied as covering equality of either opportunity or outcome. So you end up with people trying to RP as a communist equity via state regulation space empire picking the same ethos as the libertarians.
I would say how this demonstrates that flavor-wise, the Ethics are highly mutable and are best interpreted in light of Civics, the empire's other Ethics, and player RP. Egalitarianism means something very different to a megacorp than it does a communist oligarchy or a liberal democracy, but they can all be said to be championing their own interpretation of it. In all three cases it justifiably provides similar game benefits, as people feel free to express themselves and self-actualize, thus giving Influence if the empire acts in accordance with their self-actualized desires, and allowing the population to achieve incredible happiness if the empire puts the resources at their disposal through Utopian Abundance. That self-actualization and abundance might come through unbounded free market economic efficiency allowing everyone to achieve their dreams, or through state-subsidies freeing everyone from their wants.
Similarly, Spirituality probably means vastly different things to different empires--one defines it in terms of adherence to their religious dogmas, while another could embrace spirituality in a broader philosophical sense through meditation and debate. Once again, they both gain the Unity benefits, but in one that's because everyone agrees in lock-step on what their empires means, while the other could relate to a more evolutionary joint understanding of how to proceed mutually arrived at through debate.
Xenophobia might be hatred and fear of anything different as a threat, a desire to subjugate all others, or simple snobbish dismissal of it as inferior and/or inconsequential.
Militarism could represent either a focus on survival through force, imperialist ambition, or actual love of combat. Pacifism could be morally based, the result of a rational utility calculus, or simple cowardice.
These are all just the interpretations from the top of my head. There are perhaps infinitely more.
In summary, all of them are highly open to interpretation, so saying that there's a single concrete definition of what type of society any given Ethic entails is missing the point.