Not disagreeing (I'm sure you're right that he's thinking of NRT), but theoretically, you could grow stuff in an industrial wasteland without it being contaminated: you could build hydroponic facilities or some other buildings, ship clean soil in (for raised planting beds for instance), and grow things there. Just don't use the soil in the ground.

I imagine it's just not worth it to go to this trouble to grow things on contaminated former-industrial land.