One reasonable possibility is they're referring to people like Ben-Gvir who have themselves claimed that Zionism means fighting for Israeli control over more territory like the West Bank. They're the ones calling the shots right now. I don't know whether Zionists 78 years ago would've agreed, it's possible.
To some it still means favoring any existence of a Jewish state. The inertia isn't there because aside from the original partition plan being pushed by the UK, other countries have attacked Israel several times later in ways they would've have withstood without outside support.
"Zionism means fighting for Israeli control over more territory like the West Bank."
Now that is a valid use of the term. I think the problem it that Zionism means so many different things it is nearly useless as a description. It seems more useful as a slur which has become very common in some circles.
"The inertia isn't there"
I'm not sure what you mean. Are you saying Israel could be defeated without US assistance?