I just had a look around my site and was surprised to see that this wasn’t already a feature.
When a user is muted by the system after their first post, usually they are a spammer and have a blank account. These accounts are usually database noise and I think it would be great if there were an option to have these account automatically be purged. Obviously you can just click the Delete user option in the review queue and not have to deal with silencing at all but I can still imagine this would be useful.