Modify SQL query for BP's Sites Directory

blogs.php

<?php
/**
 * Modify BP's site query for non-super-admins.
 */
add_action( 'bp_include', function() {
	// If you're doing checks against More Privacy Options, make sure MPO is active.
  	if ( ! class_exists( 'ds_more_privacy_options' ) ) {
		return;
	}

  	// Modify the SQL query.
	add_filter( 'bp_after_blogs_get_blogs_parse_args', function( $retval ) {
		add_filter( 'query', 'my_filter_blogs_query' );
		return $retval;
	} );

  	// Remove our SQL query.
	add_filter( 'bp_blogs_get_blogs', function( $retval ) {
		remove_filter( 'query', 'my_filter_blogs_query' );
		return $retval;
	} );
} );

/**
 * Show all blogs regardless of "Site Visibility" setting.
 *
 * "Allow search engines to index this site" should not equate to hiding the
 * blog from the Sites directory!
 */
function my_filter_blogs_query( $retval ) {
 	 // Check for the 'public' clause.  If the clause doesn't exist, bail.
	if ( false === strpos( $retval, 'wb.public = 1' ) ) {
		return $retval;
	}

 	// Modify the SQL query to your liking.
  	// This example removes the 'public' clause entirely, but you might want to do something different.
	$retval = str_replace( ' AND wb.public = 1', '', $retval );

	return $retval;
}