Look, even if the fluid change interval is longer than 120k miles and would coincide with a rebuild, it’s still an interval, not “lifetime.” I mean, you wouldn’t rebuild the part and put back the old fluid, would you?
It isn’t an interval, though, it is lifetime. I’m apparently continually failing to make that point.
120k is only the warranty period on the drivetrain/battery, and I’m using it as an example, for parts that have zero maintenance, and are guaranteed for an amount of miles most people never even put on an ICE vehicle that otherwise requires oil changes every 3k-5k miles.
put back the old fluid
Irrelevant. Even being in the position of having a drive unit serviced at all is outside the norm or intent for lifetime of the vehicle.
an amount of miles most people never even put on an ICE vehicle
Maybe most first owners never put that many miles on their vehicle, but lots of vehicles do, in fact, get that many miles on them eventually. Those subsequent owners need to understand that “lifetime” isn’t really “lifetime” and that those fluids actually do need to be changed at some point!