IMHO WP_DEBUG allows to enable display of notices during development. If you look at the core file default-constants.php you see this :
if ( !defined('WP_DEBUG') )
define( 'WP_DEBUG', false );
So I don’t see why you should set it to false again in wp-config.php.
Regarding your issue just delete the line, WP_DEBUG should never be used on a live website, it’s a developer tool.
The fact that the constant cannot cause anything it’s a display tool. However maybe we have to admit that in a very weird universe bad things happen such as error display on a live site. If that’s the case you can leave the WP_DEBUG constant set to true and hide display like that :
define( 'WP_DEBUG_DISPLAY', false );
Your server guy should know that errors should never be shown on a live website.