filter_condition_callback in Mage_Adminhtml_Block_Promo_Quote_Edit_Tab_Coupons_Grid not working?

[Hanmac]

While checking some callbacks, I found this:

magento-lts/app/code/core/Mage/Adminhtml/Block/Promo/Quote/Edit/Tab/Coupons/Grid.php

Lines 85 to 87 in 031de28

	'filter_condition_callback' => [
	Mage::getResourceModel('salesrule/coupon_collection'), 'addIsUsedFilterCallback',
	],

Doesn't this get ignored by this?

magento-lts/app/code/core/Mage/Adminhtml/Block/Widget/Grid.php

Lines 559 to 560 in 031de28

	if ($column->getFilterConditionCallback() && $column->getFilterConditionCallback()[0] instanceof self) {
	call_user_func($column->getFilterConditionCallback(), $this->getCollection(), $column);

Mage::getResourceModel('salesrule/coupon_collection') is not an instance of Mage_Adminhtml_Block_Promo_Quote_Edit_Tab_Coupons_Grid