Thanks @Dave Olson for chiming in!
One could get around the e-unit cycling by locking it in the forward direction.
The total piece is 15" long - I still wonder how long the "isolated section" is? I imagine it would be on the short side and therefore limit its effectiveness on a number of locomotives. How neat it would have been to be able to make sizing customizeable with fastrack block ends and/or accessory activation pieces...