He does spell out why he doesn't subscribe to that approach:

"Cancer cells are not simply a disorder or breakdown in a mechanism, but an organism going on a full-tilt offensive, using multiple, often shifting strategies to produce and use molecular fuel, win resources, and evade the immune system. If so, then the rules of the game may change—these insights suggest that the war on cancer may be endless."

I don't have any expertise here, so I'm not saying he's right or wrong. But it doesn't seem to be a lack of imagination.