Another option is to filter the dropdown arguments before a call is made to wp_dropdown_pages
. This function has a hook, but it happens after the query was made.
There are two places where it can be filtered: in Quick Edit mode and the Page meta box. But none is available for Options Reading or Theme Customizer.

The following are the default arguments and an example of filter to restrict pages by author (depth
, child_of
and exlcude
seems good candidates too).
/*
$defaults = array(
'depth' => 0,
'show_date' => '',
'date_format' => get_option('date_format'),
'child_of' => 0,
'exclude' => '',
'title_li' => __('Pages'),
'echo' => 1,
'authors' => '',
'sort_column' => 'menu_order, post_title',
'link_before' => '',
'link_after' => '',
'walker' => '',
);
*/
add_filter( 'quick_edit_dropdown_pages_args', 'limit_parents_wpse_106164' );
add_filter( 'page_attributes_dropdown_pages_args', 'limit_parents_wpse_106164' );
function limit_parents_wpse_106164( $args )
{
$args['authors'] = 'author_name';
return $args;
}