Probably they don't find the algorithm for determining whether something is a product of evolution or a product of intelligence satisfactory. Especially when the algorithm is not written explicitly; there is mostly just a suggestion that after some exploring, we would know the difference.

Pieces of metal, gears, doing some work... seems like an obvious evidence of an intelligent design. Unless we consider the possibility that they somehow evolved in this strange alien biology. Or are they something like a bee hive or a beaver dam -- a product of a life form, but not very intelligently designed. Perhaps the alien "bees" create these metallic gears and assemble the machines instinctively. In which case I would expect all such machines to be rather similar to each other.

The article does not explore this interesting topic deeply enough. It just suggests that it can be done.

The Intelligent Design theorists don't seem to understand that (1) their effort to describe biological structures in strictly engineering terms capitulates to what materialists have said for generations, namely, that life operates according to nonspooky mechanical principles; and (2) their influence in propagandizing the view of the human body as a machine will probably help to erode resistance to proposals for re-engineering human biology.

In other words, the Intelligent Design idea has the unintentional effect of desacralizing the human body.

That was Caledonian. What do you expect?