Hi Mr. footyblogger,
Actually I was also using the code you mentioned and it worked as you mentioned for older versions prior to 7.0.4 version.
I have found a solution to this and it worked on my own website. Please check for my website to see the results yourself – https://www.charmjokes.com
What you have to is to edit the sharethis plugin file. Go to plugin editor and edit the file sharethis.php. Find the following code in the file.
function st_widget_head() {
adding_st_filters();
$widget = get_option('st_widget');
Now, step 1 is to remove the 2nd line from code above making it like below
function st_widget_head() {
$widget = get_option('st_widget');
Step 2 : find the code like below and comment out the first and last line as shown
//function adding_st_filters(){
// 2006-06-02 Filters to Add Sharethis widget on content and/or link on RSS
// 2006-06-02 Expected behavior is that the feed link will show up if an option is not 'no'
if (get_option('st_add_to_content') != 'no' || get_option('st_add_to_page') != 'no') {
add_filter('the_content', 'st_add_widget');
// 2008-08-15 Excerpts don't play nice due to strip_tags().
add_filter('get_the_excerpt', 'st_remove_st_add_link',9);
add_filter('the_excerpt', 'st_add_widget');
}
//}
And as footyblogger mentioned above the use of following code in the functions.php is a must
remove_filter( 'get_the_excerpt', 'st_remove_st_add_link', 9 );
remove_filter( 'the_excerpt', 'st_add_widget' );
And, you are done removing sharethis from excerpts.