How can a user get the Custodian badge with a reputation lower than 500?

Question

If I understand correctly, Custodian badge will be awarded to users who completed at least one review task. To complete a review task user should have at least a reputation of 500. (As of my understand from this page). If this is correct, how could this user get that badge?

Answer 1

Yes, access to the review queues requires 500 rep (see Privileges). However, users can also review suggested edits to their own posts. I suspect the user got the badge from this post.