So you're saying that the "language is a tool" metaphor breaks down because C is "complete" in a way that a hammer isn't. True, but that's taking the metaphor too far; it's original meaning is that the tool matters less than what you're building.
I have no problem with the conclusion that the tool matters less than what you're building.
I'd go farther and say that there is a certain tendency for C projects to "look the same" and that lispy projects "look the same" in a different way (e.g., surprisingly extensible, incorporating a language).