Agreed. Another way of looking at it is that a pure cash exchange would filter through the market demand for all goods, and as a result the nominal value of all

Agreed. Another way of looking at it is that a pure cash exchange would filter through the market demand for all goods, and as a result the nominal value of all goods would increase through the mechanism of inflation, not just land rents per the Henry George Theorem. However, there is an input consideration of identifying where this cash infusion is coming from, whether from printing money or from selling accrued assets on the open market (as what the YCombinator crew would probably be doing, if they don't already have liquid assets devoted to this endeavor).