. You don't "cite" him, you "quote" him.
You certainly do "cite him" by citing one of his articles or books that you use as a reference, whether you quote him or not. Whether he is a persuasive source is a different issue. Lawyers cite to all sorts of non-legal authority, everything from the census to sociological sources to The Federalist Papers
. In the most recent brief I filed, I cited to an article on microscopic hair analysis from a forensic journal and a compendium of DNA-related cases compiled by The Innocence Project.