Completely wrong. Myrthos means that it is so complicated that no-one could work with it. Someone has explained it once, a long time ago.
This does not mean it uses or doesn't use licensed material - we simply don't know.
All I know - the public knows - is that it was never published because it was too heavy and complex.
I think I remember that. It was in the demo days or so, someone noticed it, and then Lynn or Lar explained that it was an editor that was too complicated to use, and so they decided not to use it.