Synthetic Trees: Reduce the Culprit, Not the Source

Quoth Klaus Lackner, inventor of the synthetic tree:
If you give me one of those big windmills which have those big areas through which the rotor moves—how much CO2 can I avoid? And if I had an equally sized CO2 collector—how much CO2 can I collect? It turns out the collector is several hundred times better than the windmill.
Assuming that's correct, why is our government not on top of this thing? With regard to energy policy, they are quick to treat the source of CO2 production - fossil fuels - with costly mandates (cap 'n' trade) and arbitrary subsidies (corn ethanol), but apparently they have no interest in treating the real problem - the presence of atmospheric CO2.