I found that a bit odd too Nathaniel, so I discreetly asked around. And the explanation is exactly what Ryan said in this thread in response to you. Also apparently the deal with SEPTA is in the works. It has not been closed yet.
I wonder whatever came of the idea of converting a few of the AEM-7s that are in relatively better mechanical shape, into cabbages. They'd probably provide better protection than the Capitoliner Cab Cars in a grade crossing accident, so would possibly be desirable for use on trains that run outside of the sealed corridor with cab cars.
BTW, here's some more on 612 and 613 from someone in the know....
It makes sense to have the planned retirement sequence mostly determined by the maintenance cycle of AEM-7s and HHP-8s. Why spend money on scheduled maintenance if it is going to be retired soon? But the actual sequence is obviously going to be changed by locomotive failures. If a toaster or hippo needs an expensive repair or part and there are enough ACS-64s and remaining AEM-7s available, then off it goes to dead storage.
As for converting some AEM-7s to cab cars, I wonder if the plan was dropped due to the funding and placement of the order for the corridor bi-levels. The base order of 130 cars includes 24 cab-baggage cars. The Midwest and California corridors won't need converted locomotive car cars. So Amtrak will only need to supply cab cars for the eastern trains and they may have enough on-hand for now. They can still cherry pick a batch of the less beaten up AEM-7s for dead storage for possible future cab car conversion 5 or 10 years from now.
Some of those bi-level cab-baggage cars are going to get banged up in grade crossing accidents; perhaps the proposed 42 car option includes a few extra cab-baggage cars.
Good to hear that the problem during the #612,#613 CL move was with only 1 unit and that the damage was not serious, despite GenePoon's rather alarmist post to trainorders.
