I think you've nailed it.
It's a classic trick of these charlatans who engage in populism. They'll always aim their attack at the more intelligent/informed of society in order to pander to the egos of the less intelligent/less informed, even when they know that the arguments of the former are correct. It's one of the oldest political tricks in the book. The tabloids and mid-market papers do this all the time.
"Experts" is just the latest variation on this technique. Other common lines of attack that you hear from the Trumps, Palins and Farages of the world include "the metropolitan elite", "the sneering elite", "the intelligentsia", sarcastically pronouncing the word "intellectuals" by over-ecunciating each syllable, and so on. Basically it's pandering to people's ignorance and lower instincts, saying "These people, with their facts and information and things that you're too stupid to understand - they think they're better than you, but they're not, are they?!".
The perfect encapsulation of this was Farage's "Common Sense Express" tour of Britain a few years back. Never mind the experts - it's the bloke down the pub who knows how to sort this country out, if only they'd put him in charge. It's all quite straightforward really, we can solve all the problems in the country with just good old fashioned common sense.
Lest we forget how Farage cultivates his image at every opportunity - with a pint and a press crew. Populism at its finest.
The polls and ratings tend to lift the lid on this. Boris scores well above average on likeability and PM material but has been rated well below average by fact checking organisations. A fraud cut from the same cloth as Trump, but more clever because he's cultivated this likeable image of bumbling buffonery. Nobody suspects the buffoon of being calculating. A buffoon is dumb. A bit like us.
As I said elsewhere, there are intelligent arguments for leaving the EU (and there are populist arguments being made by the remain camp), but it annoys me no end when I see the leave side relying so heavily on these tactics because they fool good decent people, not just the mean-spirited, small-minded ones. I'm thinking in particular of those who claim to be defenders of the less privileged and less well off and seriously believe that IDS, Whittingdale, Grayling, Fox, etc are going to lead them into a brave new world of better living standards and fairness for the ordinary man and woman on the street. You just need to look at the backstory of these people - in many case, the recent backstory - to see what they're really about.