function pm_stop_product_uri($bool, $post) {
    if(!empty($post) && $post->post_type == 'product' && $post->post_title == 'Product') {
        return false;
    }

    return $bool;
}
add_filter('permalink_manager_allow_new_post_uri', 'pm_stop_product_uri', 9, 2);
add_filter('permalink_manager_allow_update_post_uri', 'pm_stop_product_uri', 9, 2);

function pm_set_custom_permalink($post_id, $post) {
    global $permalink_manager_uris;

    // Update only selected product post type permalinks
    if(!empty($post->post_type) && $post->post_type !== 'product') { return; }

    if(!empty($permalink_manager_uris)) {
        $default_uri = Permalink_Manager_URI_Functions_Post::get_default_post_uri($post_id);

        if($default_uri) {
            $permalink_manager_uris[$post_id] = $default_uri;
            update_option('permalink-manager-uris', $permalink_manager_uris);
        }
    }
}
add_action('save_post', 'pm_set_custom_permalink', 100, 2);