You seriously think he was suggesting that all experts should be ignored all of the time?
He was, to my mind, clearly indicating that experts on economic matters making their opinions known on the likely effect of brexit on the economy should be ignored. And of course the reason being that he didn't like what they were saying and the predictions they were making, which, by the way are already looking pretty accurate.
But his dismissal is also, in my view, dangerous as it provides a kind of take it or leave it view to experts, evidence and data - accept if it backs up your opinion, reject if it doesn't. As a scientist that deeply worries me, expert opinion, evidence and data should be used to inform decisions, not to justify decisions already taken.