The point of Herodotus’s equation of freedom with no-rule was that the ruler himself was not free; by assuming the rule over others, he had deprived himself of those peers in whose company he could have been free. In other words, he had destroyed the political space itself, with the result that there was no freedom extant any longer, either for himself or for those over whom he ruled.
The reason for this insistence on the interconnection of freedom and equality in Greek political thought was that freedom was understood as being manifest in certain, by no means all human activities, and that these activities could appear and be real only when others saw them, judged them, remembered them. The life of a free man needed the presence of others. Freedom itself needed therefore a place where people could come together— the agora, the market-place, or the polis, the political space proper.