"Nowhere" location rule for Advanced Custom Fields - never matches

acf-nowhere-location-rule.php

<?php
/*
Plugin Name: Advanced Custom Fields: Nowhere location rules
Description: Adds a "Nowhere" location rule in ACF
*/

add_filter('acf/location/rule_types', function($rules) {

  $rules['Extra']['nowhere'] = 'Nowhere';

  return $rules;
});

add_filter('acf/location/rule_operators/nowhere', function($choices) {

  if(isset($choices['=='])) {
    unset($choices['==']);
  }

  if(isset($choices['!='])) {
    unset($choices['!=']);
  }

  $choices['nowhere'] = '-';

  return $choices;
});

add_filter('acf/location/rule_values/nowhere', function($choices) {
  return ['nowhere' => '-'];
});

add_filter('acf/location/rule_match/nowhere', function($match, $rule, $options) {
  return false;
}, 10, 3);

More background: https://support.advancedcustomfields.com/forums/topic/ability-to-leave-a-fields-group-unasigned/