He knows more than everyone else in the room. He also knows that if he teaches them everything, he becomes less valuable. This is the Knowledge Hoarding pattern.
The fix is not to demand sharing. It is to make sharing the high-status option.
Practical Techniques
Separate Expert and Team Roles
Don’t ask him to do everything. Assign him strategy, design, and complex problems. Give the team implementation and testing. Make the split clear. He contributes at the level he built. The team learns by doing.
Frame Sharing as Mentorship
Sharing knowledge is not giving away the keys. It is becoming a mentor, which is a higher-status role than individual contributor. Say: “We’d like you to guide the team on this approach. You’ve solved these problems before. They’ll learn faster from you than from trial and error.” Make the mentorship explicit. Put it in the project plan.
Build Expert Review Into the Process
Set up a review step at key milestones. Create time for the team to bring problems to him. This keeps him central without making him a bottleneck.
Why This Works
Knowledge Hoarding is self-protection. The man who guards his knowledge fears losing his value. Give him a role that is visibly high-value. Make sharing the thing that keeps him essential.
Protect His Time
Mentoring on top of a full workload does not work. If you want him to share knowledge, build it into his job. Protect the time explicitly.