I'm convinced it's authentic robust control.
As for the tether, it not only passes power and control, but it also has oil coolant being pumped through to cool the motors that are being over-driven. So, no battery mass, and reduced motor mass, makes it possible. I was given the impression when going to a talk at DARPA that batteries would need to improve by at least 10x in power density before they could realistically remove that tether with decent operational times.