You are absolutely right. I think I mixed them up because I saw ''isolationism'' in the description.Isolationist is a tradition, not an ethos. The Basques are probably also isolationist but that doesn't prevent them from having an egalitarian ethos.
But also, the Egalitarian Ethos says in its description that ''Isolationism may be the way for others''. It would be hard to justify having both.