The structure works: we know who, what’s at stake, who’s against him, and what he has to do. Where it gets clunky: “destroy” and “destruction” come back three times in close range, and “destruction by a megalomaniac Soybean Magnate” is a passive construction; flipping it to “from a megalomaniac Soybean Magnate” picks up the pace.
The character description tells us his job but nothing about who he is as a person (“languid sheriff” or “self-centred weather man” would tell us how he behaves before the story even starts.)
The place names don’t earn their space either; a descriptor of the town and its world would tell us more than “Sweetwater, Mars” does. But the story is fun: an off-world Western with an illegal worm farm and a Soybean Magnate as antagonist places this on a sci-fi comedy shelf you can already see.
What’s missing is the sheriff’s personal stake. Defending a town reads generic until we know what he has to lose. And “megalomaniac” is the lazy version of the villain; a specific quirk on the Soybean Magnate would make him memorable.