The solution is to create a relay: "thebanned.com", then monitor who gets banned by who on inbox relays that do this type of stuff and get comments that are banned and put then there.
Now people can ...
Wouldn't it be easier to add a new NIP (or kind) that simply prevents people the user has muted from commenting on their notes? Or a "blacklist" on top of the mute list? If someone blacklists you, you wont be able to comment, DM or engage with that person at all.