I feel like the approach the author laid out near the end is passive and would lead to one assuming they have retained some knowledge. At the most, it would help someone avoid a similar bug/mistake.

A better approach would be to checkout the repo at a commit before the fix and try to replicate the solution in a short amount of time. You would then build context around what the contributor had to figure out and in the worst case you'll have a "gold standard" solution to fallback on (assuming the PR was successful).