Requiring AGPL on the contribution would also prevent a rugpull. MinIO went beyond that.

The wording gives an Apache license only to MinIO, not to people who use it. So MinIO can relicense the the contributor code under a commercially viable license, but no one else can. Everyone else will only have access to the contribution under AGPL as part of the whole project.

Presumably they've either gotten explicit permission after the fact, rewritten in the commerical product, or the contribution was too minor to be a concern. I don't think they could have put the amount of though needed to ensure they benefit from contributions in a way no one else can, and then also be unaware of license issues with any possible AGPL only contributions.