Simple.
You have a form in the page, so you must define the correct ACL for the gests to be able to edit in front-end. canEdit()
This is the incriminated line in your view :
//Check ACL before opening the form (prevent from direct access)
if (!$model->canEdit($item, true))
$model->setError(JText::_('JERROR_ALERTNOAUTHOR'));
But not only, because the model is also checking the ACL to save the item, so let's do it correctly with ACL.
I can see you don't have 'Save' button in the toolbar. So what is the porpose of having such inputs fields in this front layout ?
In short terms, what do you expect from your users there ? Can they submit informations ?