I`ve never heard the following as an argument for Christian Universalism, but am just running it by you here. According to this verse our enemies are not people but personal evil forces - the devil and his dominions. Despite His multitudinous run-ins with and judgements on people in the Bible, could the same not be considered true of God? Namely, that His main enemy is in the spiritual realm, and that we are primarily (though I realize not exclusively, for now at least) victims in crossfire between good and evil? And that the Lord will extricate us all from that position ultimately?For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms
Think of it this way - if either ECT or conditionalism turn out to be true, the poor (sometimes hapless) unbeliever will have had three forces (outside of his own fleshy nature) conspiring against him - 1) God (who ultimately condemns him to his permanent fate) 2) the devil (who on the surface was his ally but in reality wanted to destroy him) and 3) other fallen people. Perhaps one could add a fourth - natural evil in the world, natural disasters, diseases etc, though these could be absorbed into 1) or 2), depending on your theology.
As I said, I hadn`t heard this argument before but maybe it underpins some of the mentality of Christian Universalists. (?)