Ideally, I think all threads of the deleted account are better to be deleted. But this is not the case here maybe because of a technical reason or otherwise, so, I think AnonymousXYZWL makes more sense when someone deletes their account than keeping the name and only close the account. If the username is to be kept, then there is no need to delete/close the account, and the name will remain. The user can just leave the forums and not return. But some members return with new names for a new start.