I fixed it by modifying capabilities.php:1021 to be this, which seems to have fixed the issue:
case 'unfiltered_html':
// Disallow unfiltered_html for all users, even admins and super admins.
if ( defined('DISALLOW_UNFILTERED_HTML') && DISALLOW_UNFILTERED_HTML ) {
$caps[] = 'do_not_allow';
}
if ( is_multisite() && (is_super_admin() OR is_admin()) ) {
$caps[] = $cap;
}
break;