In the meantime, you can use this in your tpl_form template:
<div id="form-busy"></div>
<script type="text/javascript">
// hack to force loading indicator to the bottom
jcomments.busyForm = function(){if(this.form_id){var f=this.$(this.form_id);if(f){this.busy.move(this.$('form-busy'));}}};
</script>