They had bicycles AND wheelbarrows in 1964.
If you can prove to me that the Act has been amended, then please do so, otherwise, I'm not conceding the point.
I don't think Harvey Manning is writing books anymore either, nor do I know of any group currently pushing for Wilderness designation in the DD or closure of the Cascade River Road.
P.S. The word "solitude" occurs only once in the Act, and it's in the definition of Wilderness:
If you are going to argue this with facts, please use actual ones rather than ones you made up.