Because if you have to quadruple the number of tokens in your code base in order to make the Zig provably safe, you have 1/4 of the context window to do useful work.
Because what they did say is true for both agents and humans. Which makes it a more compelling argument than just emphasizing the specific aspect of that limitation agentic workflows.
In one comment you are presuming that agents can just ignore ergonomic problems, which would be a kind of magic if it were true, and in the next you are saying that their inability to digest enormous quantities of unnecessary tokens is some kind of flaw that needs to be called out.
Enormous quantities of unnecessary tokens are bad ergonomics for anyone, agent or otherwise.