Drupal Commerce, behaviour when you disable order status
I dig in a bit and run some custom code.

$order = commerce_order_load($order_id);
$order_status = 'payment_received';
commerce_order_status_update($order, $order_status);


and changed status. So even if status is disabled, it still is changed. Only way is to remove the status, unset it in

hook_commerce_order_state_info for whole parent state
or
hook_commerce_order_status_info
for particular status.

What happens then is if you try to change status to the one that is not there, status will be undefined.