Hi,
The user level's capability for the settings page is set to 'edit_posts' - which means this is available to even an author, let alone an editor. It should ONLY be available to administrators.
File post-thumbnail-editor.php -> line 180. Capability should change to 'manage_options'.
Thanks,
Bira
http://wordpress.org/extend/plugins/post-thumbnail-editor/
So, actually it is set to both... There are settings that authors can see vs system administrators. Try it out.
Longer version:
Authors can change the size of the thickbox interface (some people have different monitor resolutions) and whether debug is on or not.
Administrators can set which post_thumbnails are available to be resized.
If you think something is in the wrong section, let me know.