Fine. Make the map, and just realize that the sbx file is a simple text file that your friend can edit to do exactly what I said. Honestly, there is no technical difference. If one was making a game they would have sbx files and as far as I remember we don't have to do anything to encrypt the sbx file so nothing stops people from making their own maps from notepad if they wanted to.
It would seem more logical that just showing a model would be OK, but giving the source to make logical things (ie able to code) would be what's bad. If anything my suggestion is more safe than Lum's because if you make a game using LE as it is today, anyone can code via Lua because there I don't think there is anything saying you have to protect the Lua files, which means anyone could then program your game. At least with my suggestion you can take the scripting part out of it so people can't do any logic. They can just view the models.