What they actually said was this:
Depending on the question you could try Worldbuilding. However, I think it would need to be a specific question relating to building the world. Asking in general as in: would this film idea work? Wouldn’t be acceptable there or any SE site as far as I know.
If it's a question about the creation of fantasy worlds, then Worldbuilding SE might be a good bet [...] Before asking on any site, though, you should check their help centre to see if your question is likely to be acceptable there or not.
You did not follow their advice. The question you posted was not about worldbuilding, nor was it actually a question at all. You simply posted a brief summary of your storyline. My assumption is that you're looking for feedback on whether it's a good idea or not, but that is not what Worldbuilding is for. You were told that before you came here, and you ignored it.
To be clear: If you have any specific problems with developing the world in which your film takes place, then we can help you. If you have any problems with writing the actual plot of your film, we most likely cannot help you. And if you just want feedback on a story idea, then we definitely cannot help you.