it just seems to me that having what could be considered "Insurance Keys" because you might get banned is just a way to ensure you're not going to try to actually follow the rules.
I technically own two keys. Which creates an issue of how you would ever discriminate between someone who owns multiple keys because they want to support future game updates through donation, or someone who owns multiple keys because they want to completely ignore the rules of the forum without any risk of no longer being able to post?
It's not possible. So deactivating all the extra keys someone owns because you think they will use them to register again and continue breaking rules is bound to punish people who own more keys but never intended to break the rules again.
I know you didn't say this, but it's inevitable that somebody will write it in response to you as some sort of, "solution" to this problem.