nothing is ever consistent in Chile apparently haha..

Of all the times I've flown to LIM on a flight that has an onward leg to the US (mostly LA600 and LA530 when it does the whole SCL-LIM-JFK) I've always been checked for liquids, regardless of my de-boarding in LIM

The logic is that otherwise, the checkpoint becomes pointless. All it would take to board dangerous liquids in contravention to the TSA/CBP regulations is to have someone flying up to LIM and giving you his backpack while on board so you can take it the rest of the way