Wonderful suggestion. Find the right medium first.
I think programming is an iterative approach. If he's experienced with existing codebases, adding features and bugfixing, the existing structure and design might still seem like "magic" - because someone else figured all that out. That historical process become "lost art" to those not involved. While most people can learn to follow a map, very few create the opportunity to sweat out the ability to be able to create the maps themselves.
In design, there's both a bottom-up and a top-down approach. Both are required for a software developer:
1) Have the person build a small meaningful project from scratch using the very smallest building blocks (ie. stdlib). Have them build on top of that again. Make them iterate on design and codebase. Refactoring becomes a natural learning experience in its own why and how.
2) Have the person design the simplest overall system architecture from memory as free-form drawings (or other preferred method). The fewer boxes and lines initially, the better. Have them iterate on adding details for components and subsystems. The idea should form how free-form drawing is natural and the results be usable in understanding, improving, optimizing, discussing and communicating.
3) Combine #2 and #1, preferably as free-form personal projects. Just this time you start with #2. Knowing #1 is solvable by iteration; iterate on #2 and try out designs in #1. Inventions should be prototypes that are thrown into garbage bin until satisfactory design and code structure, or a better idea, has arrived.
This is by no means easy for most or not time-consuming. So a person must learn to love the processes and intricacies of discovery and invention, in order to put enough effort to improve. If there's resistance to go forward with one approach, one need to invent other approaches that works individually, so that some progress can be maintained. Developers are problem-solvers after all.
Alternatively, there might be other type of work needed to be done that suits the personality better, and where results flow easier.