One key objection to this argument is that even though a human with enough money to survive is fantastically rich relative to individual digital folk (and immensely worth expropriating from the perspective of individuals, or those in physical proximity), she can still be vanishingly poor relative to the em society as a whole. If 1 in 1,000,000,000,000,000 available units of free energy within a certain jurisdiction goes to humans while the rest goes to much cheaper digital life, national-scale digital politicians won't be able to promise any noticeable improvement in average living standards in exchange for expropriating the humans.