Hello,
I see what are you talking about and I will tell you that you are 100% safe. They can't steal any map, only those who are loaded from the server startup such as stunts, spawn place object's and stuff. In this case , you login and create your own maps which can be loaded any time by your side , not by the server's and that's the reason they can't copy them. You can feel safe and free creating maps until they are officially used for the server expect if they are event's maps so they just load for some time and then disappear.

Kind regards.