Can you say a little more about what sort of issues this is causing? Is is that he can't see the code itself because of the block colors? Or that he can't do the programming exercises because they are asking about colors in the exercise?
If something about the code blocks is making them illegible to people with color blindness, please let us know which blocks are causing problems.
Also, please tell us if particular exercises are challenging. I know that in the beginning there is a lot more with color because they don't have sprites yet, but we can flag exercises that cause particular problems for review.