When I choose SomeNewMethod and select "Create from Usage" then the method declaration is added into the private section of the class definition of pSomeClass. So the code is not compilable as SomeNewMethod is not accessable.
I didn't test if the class definition has to be special to cause this behavior. Just as an info: pSomeClass in my case is an ATL simple COM object. So there are some macros in the class definition like ATL_NO_VTABLE, BEGIN_COM_MAP and so on
This is currently a known limitation of Create From Usage. We are looking to improve this, so VA will recognise when to make the new item public or private: