change views global text field conditionally
Ok so credit goes to https://www.webfoobar.com/index.php/node/65 which basically gave me the answer.  The working code is as follows:

function MODULE_NAME_views_pre_render(&amp;$view) 
{
    if ($view-&gt;name == 'user_dashboards' &amp;&amp; $view-&gt;current_display == 'my_tutorials') 
    {
        foreach ($view-&gt;result as $index =&gt; $value) 
        {
            $tutorialtime = strtotime($value-&gt;field_field_tr_tutorial_start[$index]['raw']['value']);
            if($tutorialtime &lt; strtotime('now'))
            {
                $oldtutorials[] = $index;
            }           
        }
        $view-&gt;style_plugin-&gt;render_fields($view-&gt;result);
        foreach ($view-&gt;style_plugin-&gt;rendered_fields as $index =&gt; &amp;$rendered_result) 
        {
            if(in_array($index, $oldtutorials))
            {
                $rendered_result['nothing'] = '';
            }
        }
    }
}