If you take a bad paper shredder that, say, shreds a photo into large re-usable chunks, run the photo through that, and tape the large re-usable chunks back together, you have a photo with the same copyright as before.
If you tape them together in a new creative arrangement, you might apply enough human creativity to create a new copyrighted work.
If you grind the original to dust, and then have a mechanical process somehow mechanically re-arrange the pieces back into an image without applying creativity, then the new mechanically created arrangement would, I suspect, be a derived work.
Of course, such a process don't really exist, so for the "shapeless dust" question, it's pretty pointless to think about. However, stable diffusion is grinding images down into neural networks, and then without a significant amount of human creativity involved, creating images reconstituted from that dust.
Perhaps the prompt counts as human creativity, but that seems fairly unlikely. After all, you can give it a prompt of 'dog' and get reconstituted dust, that hardly seems like it clears a bar.
Perhaps the training process somehow injected human creativity, but that also seems difficult to argue, it's an algorithm.