I think George was saying the potential existed and if you connected a load to C thats what would happen. But yes its true if you only had load on A and B it would never get back on C no matter what.A & N can have potential to all kinds of stuff. Without a circuit path to that stuff, the charges flowing in A & N will NEVER try to flow to the other stuff.
The 10 amp neutral current on George's circuit CANNOT flow to C. It will never happen. It is mathematically and physically impossible.
Just because C exists in the world does not mean something is going to use it. Just because we have three-phase available does not mean current to a single-phase load will try to eventually travel through all three phases. That is what George proposed and it is completely and utterly wrong. Fundamentally and any other way you want to look at it.