An IP ban is not ignored in any way. If an IP is banned, they cannot actually even see anything to report. They would simply get the ban message.
There is no way in which to geographically block these, unfortunately. Feel free to add that to our feedback area. At present, the general advice on areas like this would be to remove access to guests.
While I understand a user may not want to log in, you also dont want spam. They can log in, or can use contact us to request things are removed, if they really wanted to. Of course, its up to you, but personally thats the way I would go. At present you are going out of your way for people who do not want to contribute to your site, at the expense of spam.