He's not claiming that he has difficulty understanding this magical realm of knowledge...he's claiming I'll have difficulty understanding it (or more specifically, that I cannot understand it at all).
His comparison is that of trying to explain colors to a blind man. The problem is that he's describing a very specific type of knowledge with that analogy...perceptual knowledge. Perceptual knowledge doesn't necessarily refer to anything external in reality. If this was the claim made by the EKG...or by dysert himself, then I'd have no real problem with it. I'd dismiss it without any evidence...just like I dismiss mind-readers or people who can "talk to the dead"...but at least his claim wouldn't be utter nonsense. That's not the claim that he or the EKG makes though...
He's saying that this magical knowledge he has (that I don't have) relates to reality, truth, facts. That's a completely different kind of knowledge from something that's purely perceptual. He's speaking about conceptual knowledge regarding reality. Are you starting to see why the claim is absurd now? How can he claim to know a fact/truth (concepts) without any means of conveying that concept (like words, pictures, etc)?
Imagine that you believed evolution to be true...would it be possible to hold a concept of evolution without words to describe it? Even if you're terrible at describing it...I don't see how one can claim to have knowledge of a concept without having any means of conveying that concept (even just to yourself).