You know, I am surprised we don't just code into Bitcoin to shut down if faced with a need to reorg more than 5 blocks, rather than accepting an attack chain. Then all an attacker can do is temporarily DoS a chain - far less disruptive than rolling back transactions.
Because for the low price of 250 BTC per event I could knock down bitcoin world wide as often as I want.
Also please take care here, Luke did not roll back anyone's transactions or double-spend or anything like that. He's simply mining all the blocks and not processing more transactions.