But "intellectual authority" is a contradiction. Reason doesn't work by authority.
What's actually going on is that all authority is social authority.
That "leading intellectual" has a type of social status. It comes from his socially-accepted reputation, which comes from things like socially-accepted reputation-deciders. Like the people who are socially anointed as legitimately able to decide who is worthy of a Ph.D. or a (socially) prestigious award.
(Similarly, there is no intellectual prestige. All prestige is social prestige.)