[patates]

Exactly. When people see "free, with source code included", they may tend to think that it is open-source. I hope this answer from their FAQ section clears it:

    Q. Is Lumberyard “open source”?
    No. We make the source code available to enable
    you to fully customize your game, but your rights
    are limited by the Lumberyard Service Terms. For
    example, you may not publicly release the
    Lumberyard engine source code, or use it to
    release your own game engine.