"Any thoughts on Milsted's arguments?"
I don't see a need to use some arbitrary threshold to decide an issue like this. To me, it is far simpler. The rules, the Constitution, allow for the imposition of taxes to support certain enumerated powers. The rules allow for almost every one to participate in the selection of those who decide the tax levels and the allocation of the taxes. We are all free to debate and vote on this process. As long as the rules are followed, then the process is 'moral'.
True enough, but Milsted's arguments are not about the morality of the process, but rather the basis upon which to determine the morality of the outcome.