Hi,
Here is the code.

1. Let us define a function to check if the current user has one of the ids in the lsit

/**
 * Check if the directory should be visible to a user.
 *
 * @return bool
 */
function bp_custom_is_directory_visible() {

	$visible_to_user_ids = array( 1, 2, 3, 20 );

	return is_user_logged_in() && in_array( get_current_user_id(), $visible_to_user_ids );
}

You can add your own user ids.

In case you wish to use username instead of the id, we can redefine the same function as

/**
 * Check if the directory should be visible to a user.
 *
 * @return bool
 */
function bp_custom_is_directory_visible() {

	$visible_to_user_names = array( 'admin', 'xyz' );

	return is_user_logged_in() && in_array( wp_get_current_user()->user_login, $visible_to_user_names );
}

Please note, you can use only one of the above as I have used same function name. Putting both in your file will generate error.

Now that we have written the function for checking user, we can update our code from blog to use it as

/**
 * Hide Members Directory from everyone.
 */
function buddydev_hide_members_directory_for_all() {
	if ( bp_is_members_directory() && ! bp_custom_is_directory_visible() ) {
		bp_do_404();
		load_template( get_404_template() );
		exit( 0 );
	}
}

add_action( 'bp_template_redirect', 'buddydev_hide_members_directory_for_all' );

That’s all.

Hope it works for you.

Regards
Brajesh

No Issues.

Please remove these line

bp_do_404();
load_template( get_404_template() );
exit( 0 );

and replace them with

bp_core_redirect( "http://yoursite_url");

That will do it.

Regards
Brajesh