That test shows all key requests as an estimation, in reality doing the recommended solution will more likely make the page speed slower, as the icons will be requested and rendered earlier. Unfortunately however it is not possible to move it like that, since wordpress does not support that attribute addition, so it does not really matter, the same issue would be reported either way.
You can remove this piece of code from the wp-content/plugins/ajax-search-pro/includes/classes/actions/class-asp-stylesheets.php file, from lines 109 to 126. Then clearing the cache, and it should not be there anymore. That should do the trick.