One of the points of design patterns is to define a common language. The benefit of this is that it helps people understand one another. The fact that delegation as discussed in GoF is what everyone understands delegation to be is good enough reason to continue using the word "delegation" that way and to force him to find a new word for what he wants to say. Even if his definition was first.
But his definition was NOT first. Sure, someone may have first used the term in OO programming in his sense of the word. But the word "delegation" has long-standing usage in the English language. It means, "Doing this is now your responsibility." In English there is no automatic implication that the person to whom things are delegated necessarily has access to the person who did the delegating. In practice, of course, there is. Which is why the software analogs include that. But in the real world it is clear when you intend to refer a question back to the original person, and when you do not. Therefore the long established and universally understood definition does NOT indicate that the person to whom you delegate has the option of choosing to intercept any and all questions you ask.
So which behavior is preferable?. If I delegate to you, and then need to be aware of all of the methods that you define, all of your methods, both public and private, become part of the surface of the API between us. However the whole point of modularity is to have limited APIs between you and your components. Enlarging the API may be easier and more convenient, but it entwines code into spaghetti and is bad for your code base. So good software design says that of the two possible definitions of "delegation" we are comparing, we should prefer the one that makes it clear in the delegated to method when exactly it intends to go back to the delegated object versus when it is trying to send messages to itself. And the version that does that is the version that the Gang of Four used.
Therefore he is wrong to say that delegation should be redefined to mean what he means. He is wrong to say that his definition is better grounded in the history of the word "delegation". And he's dead wrong that implementing his version of the word "delegation" is better software design than the current definition.