Reasons? He likes the "principle" of "net neutrality" and he also likes the idea of "sav[ing] money on lobbying fees" by having a President who will respond to Cerf's every desire.
Don't believe me? Read this.
I guess it is true what they say. Barack Obama will run the lobbyists out of Washington. There is, after all, no need for middlemen to occupy the space between Obama and his political benefactors when the latter group comes by to collect the quid it was promised for its quo.