It appears that you're right. I put too much faith (any at all) into the poster who put up that text in the first place. We should estimate the temperature shift required to produce our energy:

The electricity economy is, by those old estimates: 1.69521e12,

The temperature of the solar radiation is: 

The area of earth is: 510,065,284.702 

The cross-sectional area that earth presents to the sun is: 

Hence the (self-consistent) estimate of the Earth's effective temperature is (ignoring electricity): 

.

Subbing the electricity demand in

Net difference:

There is clearly more than enough thermal radiation to satisfy our needs. We should remove that section.