function maybe_skip_import( $user_meta, $contact_id ) {

    $tags = wp_fusion()->crm->get_tags( $contact_id );

    if ( in_array( 'No Import', $tags ) ) {
        return null;
    }

    return $user_meta;

}

add_filter( 'wpf_import_user', 'maybe_skip_import', 10, 2 );