add_filter('pre_get_posts', 'event_cat_permissions');

function event_cat_permissions ($wp_query) {

    // Include all posts on admin views
    if ( is_admin() ) return $wp_query;


    $exclude_cats = array();

    // Exclude cats if not admin... copy/modify this logic for each custom role
    if (!current_user_can('administrator')) {
        $exclude_cats[] = 'exclude-slug';
    }


    // Join with current tax query if set
    if (is_array($wp_query->tax_query))
        $tax_query = $wp_query->tax_query;
    else
        $tax_query = array();


    // Setup an exclude from the tribe_events_cat taxonomy
    $tax_query[] = array(
        'taxonomy'  => 'tribe_events_cat',
        'field'     => 'slug',
        'terms'     => $exclude_cats,
        'operator'  => 'NOT IN'
    );

    $wp_query->set('tax_query', $tax_query);

    return $wp_query;
}