It's not a diagram or mock-up, it's a direct representation of the real thing for computer simulations, similar to CAD. The dimensions and shape of the components are accurate. And the author is calling it a logo because the picture is used to represent and advertise the software.

It's a product diagram on a presentation slide. Hopefully meant to be read on handouts or proceedings.

A logo is the Sierra stylized text in the lower center.

And the two others in the slide's footer.

That Sandia might use, what was obviously intended as a diagram as a logo is a whole other thing but doesn't make it one.

As long as all representation of that thing are that big and readable one can assume they were not used as logos.

The author of the post claims that the warhead-like design "is literally the logo for this particular software framework." I can't verify this claim, but other Sandia frameworks (e.g. Sierra) use similar, equally overdesigned logos, so it's plausible.

<https://news.ycombinator.com/item?id=41464358>