The aliens' plans were, if I remember right, posted for display in a nearby star system, with a similar 'it's your own fault if you didn't bother to go look' justification.
The indie book series Dungeon Crawler Carl, which is entirely unlike Adams' work in most ways but clearly takes some inspiration from the malevolent absurdity on display, uses a similar premise where the demolition-causing aliens let the pharaohs know 40,000 years ago and that serves as sufficient legal notice.
The indie book series Dungeon Crawler Carl, which is entirely unlike Adams' work in most ways but clearly takes some inspiration from the malevolent absurdity on display, uses a similar premise where the demolition-causing aliens let the pharaohs know 40,000 years ago and that serves as sufficient legal notice.