I don't believe Neo-Platonism, in which Platonic forms have some kind of causal power, whether directly or through an intermediary, is Intelligent Design proper. This is because the Platonic forms are necessary entities, and insofar they are necessary their instantiation in turn exerts necessity upon the instantiation.
However, if the causal agent that brings a particular object into being is necessitated in doing so, then that object is a product of necessity, at least in some way. Per the CSI criteria, said object does not possess complexity, as it has a probability of 1. On the other hand, perhaps it has a probability less than 1 but greater than 0. In this case, Neo-Platonism does not explain the existence of the object any better than materialism does.
This argument is very similar to the proof that ID implies the supernatural, in which Neo-Platonism is substituted for the physical laws of chance and necessity.
That being said, Platonism does serve a very valuable purpose for Intelligent Design in that it provides an objective specification.