Did you read it? It was a literature review. He made no claims himself other than a review of the available literature on the impact of migration controls on economic activity. You've taken a piece of work and chosen to critique it based upon the actions of someone who chose to review one of your past books, which I believe has nothing at all to do with economics, migration or anything of the sort. Indeed, I'm not really sure how it applies?
I've no qualms at all with you disputing what has been written, but at least dispute it with something better than "all academics are idiots, what do they know...".
I mean we've been told that migration isn't a major issue in the leave vote, with control the real cherry, so I presume you accept that it's feasible that if an increase in migration is better (or completely open borders to the world rather than just the EU) then that should also be on the table.
Presumably if we are to understand the impact migration has on the British economy, the European economy, and indeed the global economy, then we need people to study those impacts rather than stick our finger in the air and hope divine intervention happens to strike it