Problems with 2004 GTO

I reflashed a 2004 GTO PCM to remove VATS, rear O2s, and emissions (using Tunercat). The owner was not able to get the engine to run. A second look at the PCM showed no obvious problems with the flash. The PCM was sent to someone else (don't know who) and they told the owner that he had to remove something else that had to do with the communication to and from the BCM. Can someone shed some light on this? I'm not aware of a flag that has to do with communication to the BCM.

Thanks