The author notes "if each one were to receive $17,500 per year, that would mean an annual cost of $4.38 trillion, which is more than entire $3.5 trillion federal US budget" but then quickly jumps into taxation modeling forgetting such government trivialities as Medicare, Social Security, national defense, interest on previously issued government debt, federal highways and various other federal expenditures.

While you have a new expenditure category that is "more than entire $3.5 trillion federal US budget", the old categories are still around, so that 50% tax rate should perhaps be doubled up.