I've just found there already is a Nautilus option to turn off the "executable text file" message: Edit > Preferences > Behaviour > View executable text files when they are opened.
Turning this on does prevent scripts from being run from Nautilus, as the Nautilus right-click menu doesn't have a "run" option, but it would seem unlikely that a new user would want to do this.
This would appear to be a duplicate of Nautilus bug #14335.
I've just found there already is a Nautilus option to turn off the "executable text file" message: Edit > Preferences > Behaviour > View executable text files when they are opened.
Turning this on does prevent scripts from being run from Nautilus, as the Nautilus right-click menu doesn't have a "run" option, but it would seem unlikely that a new user would want to do this.
This would appear to be a duplicate of Nautilus bug #14335.