Well, if it's just an indicator, why not delist automatically on request, as other blocklists do? It seems inappropriate to charge for this.

And not just charge. You need to get a subscription even!

Theoretically speaking, a person could get themselves blocked, request an unblocking, and keep on spamming, hoping they won't get blocked again.

Because they don't want to. You can create one too and add whoever you like to it.

The problem is either with other things raising your scores (very likely) or with Orange dropping traffic based on the wrong list (unlikely)