Why Does Obama Keep Doing This?

In 2007 Obama assured us he would make sure that GMO's were properly labelled and the American people kept informed of this intrusion on their food supply.  Last week he signed the Monsanto Protection Act that protects the company from any legal action in GMO's.  Why does he go all weak in the knees when dealing with large corporations?

http://www.nationofchange.org/obama-signature-monsanto-protection-act-ignites-massive-activism-1364569139