The Bible is written in such a way that only those with the right attitude would understand its message. People with a proud attitude—a common trait of “wise and intellectual ones”—tend to misunderstand the Bible. But people who read the Bible with the attitude of “young children”—humble and eager to learn—are rewarded with a better understanding of God’s message.
They've been saying this for years. I remember as a kid, if anyone who appeared 'too smart' or 'too proud', older JWs would pre-judge them as unable to accept the 'truth'.
It's a combination of 1) confirmation bias - JWs are mostly uneducated, mostly simple folk, so in theirs minds, and as confirmed by the WT leadership, only the humble, uneducated are drawn to the 'truth' of the Bible and 2) a red herring argument - using the question 'why is the Bible misunderstood' to conclude, without evidence, that 'wise and intellectual ones' (or 'smarter than your average JW') cannot be drawn to the 'truth' of the Bible (or in other words, make good, obedient JW robots)