Ohh i think i have misunderstood you in the first place, but now i see what you meant;
To show the "availability" icon if the product is out of stock; open this PHP file:
/templates/YOUR_TEMPLATE/html/com_virtuemart/productdetails/default.php
find this line (line#314):
if($stockhandle=='disableadd' and ($this->product->product_in_stock - $this->product->product_ordered)>=1){
and replace it with this:
if($stockhandle=='disableadd'){
then you will start seeing the availability icons even though the product is out-of-stock.
Regards.