He means that solar and wind power (and other renewable energy sources) represent only a tiny fraction of power generation in the US. Therefore, using them as a justification for the "clean" generation of hydrogen just doesn't make the case.

He is right that they are indeed "rounding errors." The DOE's own data shows that "Wood, black liquor, other wood waste, biogenic municipal solid waste, landfill gas, sludge waste, agriculture byproducts, other biomass, geothermal, solar thermal, photovoltaic energy, and wind" contributed to only 3% of total energy production in the US in 2008. [1]

[1] http://www.eia.doe.gov/cneaf/electricity/epm/table1_1.html