Cool, but now anyone can access the course.
I just thought, what if I could do this for an authenticated user? And you can!
- In the course go to: Settings > Course administration > Users > Permissions.
- Go down to: View courses without participation (moodle/course:view)
- Click the plus symbol and then select authenticated user.
I don't know if some things would be blocked but I'm sure it would be easy to change the permissions.