Comment by mobelkh

throw his garbage out, the time and effort taken to review that is magnitudes more than what it took to prompt it.

have him start with an overall design doc if his change is 15k, it's definitely worth a design doc.

and then have his contributions reviewed in pieces of 200-300 LoC PRs.

any other solution is trading stability and system knowledge, that's 15k LoC no one is truly familiar with, even if you do try to review it