This code should exclude shop_order comments from queries. Some queries (like the recent comments widget on the dashboard) are hardcoded.
and are not filtered, however, the code current_user_can( 'read_post', $comment->comment_post_ID ) should keep them safe since only admin and.
shop managers can view orders anyway.
The frontend view order pages get around this filter by using remove_filter('comments_clauses', array( 'WC_Comments' ,'exclude_order_comments'), 10, 1 );