I don't think they mean a specific McMansion Hell post, they want something in the style of the blog itself where humanity/earth is the McMansion and the alien is the critic. For example you'd have an alien write up their visit to a human suburb with pictures of the manicured lawns that they've covered with arrows and text boxes dragging all the absurdities, like "aggressively wasteful monoculture accented with canine feces, it's giving [hated enemy empire]".