Hi,
In navigation you can't use security role instead use specific entity permissions, and then refer this entity to control the navigation.
You can include this entity under the specific roles for which you have to show/hide navigation.
For example let's say you created entity called UINavigationControl, and now on your sitemap you have using Create permission for this entity to hide/show particular subarea, If you want to show this navigation to particular security role, add create permission for this entity, so all the users who have this security role will be able to see it.
And for those security role you want to hide this subarea, don't provide create permission for this entity.