To set the record straight, they are not saying the sales tax is a VAT. They are saying his proposed income tax, because it lacks a deduction for wages, functions as a VAT.
That makes even less sense as a VAT is a production level tax on all levels of production of a good. It has nothing to do with VAT also.
It is still a matter of gross versus net. The fact is that the 999 plan replaces income, payroll, and corporate taxes that can eat up over 50% of your pay, be it through income or hidden sales taxes, and replaces it with a clean, out in the open, system.