Add field to an entity_view for dispaly in a tapir table in ubercart
So this is the ugly hack I used to resolve the issue:

  if (!empty($order-&gt;products)) {
    $build = entity_view('uc_order_product', $order-&gt;products);
    foreach($build['uc_order_product'] as $line_item) {
      $node = node_load($line_item['#entity']-&gt;nid);
      $vendor['#markup'] = '&lt;a href=' . url('user/' . $node-&gt;uid) . '&gt;' . $node-&gt;uid . '&lt;/a&gt;';
      $vendor['#cell_attributes']['class'][] = 'vendor';
      $line_item_id = $line_item['#entity']-&gt;order_product_id;
      $build['uc_order_product'][$line_item_id]['vendor'] = $vendor;
    }
    $table['#rows'] = $build['uc_order_product'];
  }