I’ve pushed a fix for this issue to the plugin’s repository. That code will get reviewed and hopefully added to the plugin soon.
For now, the advice I gave you about disabling the feed was wrong. To prevent feed topics from being created, you need to re-enable the plugin, then go to the RSS Polling settings link. On that page, delete the Feed URL that you have entered.
Once you have done that, feed topics should no longer be created.