When I first read this I thought it was a nice way of pointing out the dangers of an aristocracy – the exact thing the 18th Century Enlightenment thinkers made their reputation attacking. At that time, the awfulness of society was seen in part to be the result of the establishment being ill-educated and having been merely born into their positions of power.

I read this as saying:

The best argument exemplifying of an elitist-aristocracy is ‘you shouldn’t have to know something in order to be in charge of it’

or perhaps

By their example, “in favour of this” they show the limitations of thinking that people shouldn’t need to know something in order to run it.

But then again, is it a defence of elitism? His Goldsbie actually saying:

“The best argument for an elitist society is the example of those people who think they can run things without knowing anything about it. We should have an educated elite who know what they are doing.”

Je ne sais pas.