Less WIP is better for the throughput. If you saturate all the review bandwidth you're just wasting your time creating more PRs, the time would be better spent helping others get their PRs merged.
The reviewer gets to merge the PR so their name appears on all the great new features and they are credited for them. That would end his unfair behaviour of dumping effort onto other people.
The solution is that he spends more time scoping the size of the PR so that it’s reviewable and understands the code he’s submitting well enough to have discussions about it. And that he does so human to human so that they can come to mutual understanding.