The software is closed source, and aside from the borrowed code, is entirely my own.
Unless I've completely misunderstood the question, that would be violating two of the Creative Commons license's restrictions:
- That it can only be used in non-commercial contexts
- That any derivative works be licensed under the same license
I really don't know how you thought you could use CharacterController2D in a commercial closed-source app! That's the exact opposite of what the license is for!
I contacted the author directly. They said that it is OK to use the code commercially as long as it is used as part of a compiled and closed source greater project. It is not allowed to sell his actual code stand alone or as part of another code base.
So the code cannot be sold, but you might be able to obtain a different license from the copyright owner.