Come on, it's a Sony, everything is proprietary...
Just kidding (maybe not). I'm not sure, but knowing Sony I'll bet they made it different than a standard PC power cable on purpose.
Have you thought of running power (via Romex cable) to an outlet behind the TV. Then just use the stock power cable into the new outlet.
I think having power cords that long are probably a code violation. So it might be hard to even find one that long.