Can you start him with JavaScript and basic web development instead? That's how I learned around that age (started around 5 or 6). The immediate feedback of being able to change something in text and immediately see the impact was a big thing that helped me. Likewise, something like helping him mod games he plays might be good.

Scratch always kind of struck me as a non-programmer's idea of how to teach children to code personally. (Or at least programmers that didn't start/weren't active as children).