Up until a few months ago, I was an engineer for OSC. We used the same Flight Termination Logic Unit (FTLU) as Antares. I can confirm that it can provide for automatic destruct should the engineers desire it. I have no knowledge of the specifics of its use in Antares (I did not work on the Antares program), but given the constraints of operating from Wallops, I would not be surprised if automatic destruct is enabled for all Antares launches.