The author's intent was a great idea. However, after installing this plug-in, false-positives began to occur (despite being sure to keep the range syntax correct.)
Issues with category pages and posts arose, whereby legitimate visitors were incorrectly redirected to the ban page.
Final mitigation entailed having to restore the site back to a previous day's back-up image, prior to when this plug-in was installed. This included restoration of WordPress' MySQL database, as well as all files.
Others may not experience the same challenges. As is the case with plug-ins generally, sometimes incompatibility issues arise depending on the combination of plug-ins a particular WordPress site may have.
However, I do strongly recommend that all sites that wish to try this plug-in -- first backup their WordPress database, as well as all site files.