If someone makes a level on another CodeCombat server in their own database, they can share that with other CodeCombat servers all they please. We are just being cautious about the levels that end up in the main codecombat.com database, because at some point we might want to either make premium-only campaigns or allow others to sell access to their campaigns, and we can't do that if the levels are all MIT.
Hopefully we can keep all levels free for everyone anyway, since recruiting is looking pretty good as a monetization strategy so far.