Eng 6597 union parameters

1. The choice was between adding this special-case accessor to the parent class or implementing the behavior on the derived class, but the latter would imply opening up the data member (or a more generic accessor) to allow protected access. I thought that this was the better option, given that the name would indicate the intended use case.

2. What are you missing? 
I guess that would be the intent of the word "summary" in the first sentence. 
Also, the whole point of the second sentence which was my specific attempt to clarify this.
Is there a clearer way to expel the false expectation (which I originally shared, thus this attempt to disavow it) that every child statement at this stage only references a partial parameter list related to what it actually references?