That seems a little strange, load shedding all those services during fuel jettison, the IDG outputs must be pretty 'close to the wind', as regards electrical capacity!
The 767 was Boeing's first twin/ETOPS aircraft so there was a tendency to over-engineer it. The fuel jettison loadshed in the earlier aircraft was designed to operate only when the aircraft was running on a single engine. Having said that, later aircraft appear to have been modified to load shed running on both engines also. Perhaps loadshedding the entertainment system is one way of getting the pax to listen to the flight attendants go through their emergency evac instructions?
The B737NG doesn't load shed at all during fuel jettison!
er... Hooray for the NG! Nevertheless, it does have a generic loadshed system which covers Galley or Cab/Util systems.
Does the NG variant you speak of use additional pumps for fuel jettison? (i.e is there an additional requirement for the NG to have fuel jettison loadshed nayway?).
Rgds.
NSEU