I've watched Whiteside play. His basketball moves appear fluid and quick. He makes quick decisions with the ball and doesn't hesitate. Throughout history, a good warrior didn't need a high mental intelligence (measurable anyway), to be effective. Some people have learning disabilities and just never got the right specialized training in school to be good communicators and/or students. Whiteside, from what I've seen, appears to be the visual type. He seems to be able to recognize patterns quickly and then act based on what the pattern dictates he do.
Basketball really isn't that complicated when you simplify it to recognizing patterns. Isn't that what the Jazz offense is? Isn't that what the Triangle Offense is? I'm sure once Whiteside memorizes the patterns that the offense creates, he'll have no trouble running it.
Also, I'm sure by now he knows how to effectively communicate with his teammates and coaching staff. Isn't that all that matters? Yes, he'll have to give interviews with the media but he'll improve with time. Every player eventually learns all the cliches and quick answers to use, to end an interview quickly, if need be.