This seems to make a bit of sense. NJT hates their EMUs, SEPTA doesn't seem to be too fond of the AEM7/push pulls, so why not trade a few? The Comet 6 isn't all that great an increase in capacity over the previous single level Comets, its main advantage is that it has all 2+2 seating and more standee space. I would say that SEPTA should give the 6 AEM7s to Amtrak for Keystone service, with the sole ALP44 going to NJT, but then NJT potentially would be stuck with cars they cannot haul, and Amtrak potentially would have locomotives with no cars to haul. However, can the Arrow IIIs be MUed with the Silverliner IVs? I know the ABB rebuild did retain the ability to MU with the Arrow IIs, but I don't know if the SEPTA and NJT EMUs were ever compatible.
However, why would SEPTA want the Arrow IIs? Didn't they have PCB using transformers? AFAIK when NJT retired the Arrow IIs SEPTA had just finished Frazier yard, completed abandoning Paoli, and was retrofitting the Silverliner IVs with PCB-free transformers. I know the Arrow IIs lacked dynamic brakes, so either SEPTA would have to follow NJT's lead in retrofitting them, or would be forced to have a bunch of what would basically be younger Silverliner IIs and IIIs running around, complete with the flukey handling in mixed sets and the high wheel wear.