…and if this game was released in '89, it probably *would* have done that.
However, LSL2 released in Oct '88, it was the immediate follow-up to Sept's KQ4.
Its important to remember that the SCI0 engine wasn't an atomic "thing", instead it was constantly evolving behind the scenes. In this case, the SET_PALETTE commands hadn't been implemented yet. They do not appear *at all* KQ4, LSL2, or PQ2. Meaning, they pretty much were stuck with the default palette.