it certainly strongly suggests that the IFE/PASS SEATS switch takes down all passenger cabin telecommunications.
I agree, however the aircraft I fly has the same switch and it doesn't cut off the Cabin SATCOM link.
The FI references the CPMU; the Cabin Passenger Management Unit, which provides an interface between the Panasonic IFE and the SDU, for any Data-3 SMS/e-mail messages.
It would be very interesting to find out more about the CPMU to ascertain if it is de-powered by the IFE switch.
I can see good reasons why it would
not be, particularly if it also controls cabin lighting, cabin comms and PA functions. Unfortunately I cannot source a reference for what it does.
If it still works after the IFE is de-powered, and you can send SMS/Emails via the SATCOM with it, then that would be a reason to de-power the LH AC Bus.