I have gone through all the links you posted; none lead to an explorer where the said 15 bitcoins were just burnt. All the links are talking about the explanation of burnt bitcoin and what it means.

And for the record, personally I don't consider any Bitcoin which stays under the address with a private key as lost forever, as long as there is a private key attached to the address.

Even if the key is lost, it could be considered to be temporary, as the chance of recovery might be slim but it's still there. Bitcoins which I am to burn are just like the recent hack carried out by a group of hackers which claims to be Iranians.