fix_ampersand_permalink.php

add_action( 'pbs_pre_save_content', 'pre_fix_ampersand_permalink' );

global $is_saving;
$is_saving = false;

function pre_fix_ampersand_permalink() {
  global $is_saving;
  $is_saving = true;
}

add_action( 'pbs_saved_content', 'fix_ampersand_permalink', 999 );

function fix_ampersand_permalink( $post_id ) {
  global $is_saving;
  if ( $is_saving ) {
    $possibly_wrong_perma = esc_url( get_permalink( $post_id ) );
    die( preg_replace( '/&?#038;/', '&', $possibly_wrong_perma ) );
  }
}