Moodle Course Renderer Hidden Topics

I'm trying to show a graphic if a topic/section within a course has access restricted by an Activity completion condition and is shown greyed-out with restriction information. I've had limited success, within the course renderer function `section_left_content` I have tried using `$thismod->available` and `$section->showavailability` to check whether the topic is restricted, both work for admin users, however both variables are null for students therefore the check fails. Is there a better way to do this? It feels like a *role permission issue*. Using Moodle v2.5.2, Topics course format.