I think it’s pretty clear from that statement. That said, you can’t “reserve” an idea.
Otherwise you could create a post proclaiming you were going to make a number of mods with every possible category known to man.
“John” creates a Lord of the rings mod, but after a few weeks, months, or years he abandons the mod and does not respond to any queries regarding someone else continuing the mod.
There is nothing stopping you creating a LOTR mod yourself, you just cant use that persons models and/or code. Just look at what is happening right now… there is a Viking mod being created, despite the Norsemod existing for a number of years.
I could also, for example create my own auto-harvesting mod, archipelago biome mod, or create a mod with my own implementation of fishing - as long as I didn’t steal or butcher the hard work that Bruno or Pawel had produced and I created them both from scratch.