I recon it's a stunt too, however I think there is some sneaky reason behind it all. I recon the reason it's 18+ isn't to do with quality of ideas, it's that the target audience of this attraction is adults. They did say it's going to be a thrill-seeker ride. I recon the winners (yes plural) will be a team of people who will be used like a market research panel with regard to name, marketing and some theming aspects.
It's hardly going to actually be anything to do with designing the ride... I've entered on the basis of why not? It's a good opportunity to get to talk to, meet and greet people within the company for whoever wins
I'd say it's probably for the best if anyone thinking of entering this doesn't harp on about being a coaster enthusiast; it's more likely to put them off than interest them.
I always thought that, but you'd be surprised. I've found that working knowledge actually really interests them. There are a lot of enthusiasts working in the industry, it's just that most aren't typical enthusiasts, they are people who are "enthusiasts" of the leisure industry in general, or of themed spaces in general. It goes back to what you said in the other topic though, there's a difference between types of enthusiast. "I go to alton towers 50 times a year and I love Nemesis!" won't impress them, but I recon that generally showing a working knowledge and interest that's not so specific might?
Though, if I'm right about the 18+ thing, playing a wild card of "I'm just your average 20 year and I'm a thrill seeker" might also work.