Notably, Xanatos and Shego both control major port cities. They have undisturbed import/export routes to the rest of the world. Consequently, the gutting of many of America's major farming regions by the combined "wasteland" regions associated with AUTO and the Tempest Domain doesn't affect them as badly. But Doofania is landlocked and its economy is heavily damaged by the cutting of trade links in certain directions. That's not to say we can't import food, but food prices could easily skyrocket under the circumstances.
Though I'd also point out that they are more the 'megacorp but US goverment' types, so it's not sole responsibility. To add to that, Shego... honestly I think it's worth remembering that Shego is a bad person. Like, yes, she's a nicer king, but only because she's neither actively malicious (Doom, Bellweather, Syndrome) or the end of humanity as a free species (Toffee, Bill, Dor). But she still regularly tries to kill teens, showed little remorse over the idea of killing a kid*, and racing over the world dictator style. To add to that, she is noted in her write-up as being lazy and focused on only super/extraordinary individuals. All of which adds up to her domain likely looking like a lib-right hellhole, with ultra mansions if you are useful/powerful, but serious, ongoing food insecurity among the poor and occasionally working class.
*Yes, one who fought her in the future, but still
More important note - didn't the deal come around over a turn after the tacos got blown up by him?
Yup, which means he started paying attention to earth and wanted a pawn to start with, and with us being seen as an idiot who cares about feeding people...
His options now are either worry about us (because we are being suspicious and he needs no-one to know his real goals) or shrug and move on. I hope for the second, as his intrigue is likely to be high enough to do some serious spying. If he shrugs and moves on, Glomgold seems the next obvious target, talking up the corn via the amount he can sell it for.
