Since they don't have MU cables the second train is dead in tow?
Yes. The brakes are compatible, so the one train can pull the other.
How will they J train two Siemens trains? With one train dead in tow? And what if the first locomotive has an issue? You cannot use it as a cab car. Is that not an issue?
Nobody said that Siemens trains can't MU with each other.... they just can't MU with older trains.