Not a loophole, it's because @larkenrose started off by uniquely criticizing representative government.
Though I did make it clear that a sufficient group of people elect a representative government to whom they confer wherewithal to govern. Of course, you are not represented if you didn't vote, under the current system. I would actually favour a different style of representative, not vote-based, but based on models which align representative's interests to unique group of people. That way this problem would be avoided.
Even under the current system, "authority" just means individuals to whom governing rights (not in a moral sense) are consensually conferred by a particular group of people. Since they're appointed to govern a land, yes they may rule over you. But it doesn't change the fact that it's a consent-based system, that would exist in any society where humans have the ability to exercise choice, because it's a pretty efficient system of governance.
On the voluntary obedience point. Yes, true. But this would almost certainly exist in any social organization, where a group of people have an incentive to enforce certain rules. At least in the present one you can influence the pooled government.
I could just as well say that breaking delegative consensus (effectively breaching a contract) is immoral.