It's not about the content license, it's about importing the content directly from another game. A fan could have made their own "joux plane", and the only complaint might be the confusion over the name, and that's a stretch. Like we're bound to get a Nordschleife before the official one arrives, and even if it's completely user-made KS may want the only nordschleife to bear the registered trademarks to be their own official, licensed circuit.