There’s no problem using CHttpRequest::getParam() to get a single param which is an array, just like done when using _POST or _GET. You get the same thing in your hand:
Yii::app()->request->getParam('Modelname')
and
$_POST['Modelname'];
Are the same… .
Only that the former is more portable and (arguably) cleaner. If the two are equivalent, then whatever is done in setAttributes() is irrelevant.
This is surely not a significant issue but I guess its worth the fix, to maintain and enhance Yii’s “Professional” mission statement.