"You reported an estimated $100,000 in income from Google in 2007"
Given what it is claimed he was doing and his status in the US political arena, this doesn't seem very much. The lack of information and phrasing of the attack seems to imply that earnings from Google in other years was significantly lower or non-existent.
So this does seem like a continuation of the modern obsession with digging over politicians pasts and making a mountain range out of a single mole hill...