Larry Kudlow has not been an economist in at least a generation. Rather, he plays an economist on TV. Whatever ability he once had to make or analyze or present coherent and data-based economic arguments is long gone—with a number of his old friends blaming long-term consequences of severe and prolonged drug addiction.
The right way to view this appointment is, I think, as if Donald Trump were to name William Shatner to command the Navy's 7th Fleet.
That said, probably little damage will be done. The major day-to-day job of the NEC Chair is to coordinate the presentation of economic policy options to the President, and to try to keep the agencies and departments on the same page as they implement policy. Kudlow has negative talents in either organizing and presenting alternative points of view or in controlling bureaucracies. Therefore the agencies will each continue marching to its different drummer, and there will be no coherent presentation of policy options to the President. But that will not be new.