Just one anecdote that supports your son’s decision–
We have a family friend whose son attended the University of Edinburgh. He wanted to go into real estate finance. When he returned to NYC he could not get a job in his field, at all, and he tried hard. He ended up getting a masters at Columbia (cost him $$$$), he just graduated and is now employed in his desired field.
Plus your son can always go to the UK for a masters, if he wants that experience.