I'd really be interested in knowing what your folks were trying, Patrick.
I don't think the system power (VCC) is actually going through the VCA per se. I think the EG is just spitting out the same voltage that drives its built-in VCA as its "signal." I imagine if you measure the power input voltage on the bitsnap, and the output voltage on the other bitsnap, they'll always be the same, regardless of how you set the EG. I haven't looked at the schematics, but this is what would make sense, and really, it's the only way it COULD be working, otherwise anything downstream of the EG (when working as a VCA) is not going to be getting its expected 5V. Like the speaker, for instance.