Perhaps, but it is not updating the LTN92. It may be updating the position that is derived and displayed but it does not update the IRS.
Actually, it is. The Litton is taking the GNS inputs, using them for updating, and providing a continuously updated and corrected position using those inputs. It is not processing through a FMS or FMC. The INS is not inputting as a sensor into a multi-sensor unit which then combines the signals. The GPS inputs to the Litton to update it, and the Litton provides the position.