How is it not a nanoscale robot? It is a nanoscale device that performs the assigned task. What does a robot have that the nanoscale anticarbon lump doesn't?

I admit that it's not the sort of thing one thinks of when one thinks of the word 'robot' (to be fair, though, what I think of when I think of the word 'robot' is not nanoscale either). But I have found that, often, a simple solution to a problem can be found by, as you put it, 'walking around' it to get to the desired outcome.