gistfile1.php

<?php
function exclude_cats() {
    if( ! current_user_can( 'manage_options' ) ) {
        add_filter( 'list_terms_exclusions', 'exclude_args', 10, 2 );
    }
}

function exclude_args( $exclusions, $args ) {
    $current_user = wp_get_current_user();

    if ( strpos( $current_user->adi_title, 'Support' ) !== false ) {
        $parentcat = 26;
    } elseif ( strpos( $current_user->adi_title, 'Sales' ) !== false ) {
        $parentcat = 27;
    }
    
    if ( ! isset( $parentcat ) )
    	return true;
    	
    $included[] = $parentcat;
    	
    $children = get_categories( array( 'child_if' => $parentcat ) );
    foreach( $children AS $singlechild ) {
    	$included[] = $singlechild->cat_ID;
    }

    return $exclusions . " AND ( t.term_id IN ( " . implode( ",", $included ) . " ) )";
}
add_action( 'admin_init', 'exclude_cats' );