There are several explanations that I'm aware of as to why the Easter Island culture collapsed. While Diamond put forth a hypothesis of deforestation, soil nutrient depletion and cascading environmental effects, I'm going to limit this question to a rival hypothesis: disease and slave trade from European contact.
Suppose a Rapa Nui mystic has a vision about the dangers of foreign peoples arriving on gargantuan and fantastic sea vessels. His divination / interpretation of this vision was:
- Do not fight these foreigners
- Prevent contact as much as possible
- Do not underestimate their technology
Supposing that this mystic had absolute authority into influencing the Rapa Nui court at the time, could Easter Islanders prevent landfall at their level of technology?
Note: Population of Easter Island at time of contact was said to be ~3,000.
Note II: Would also be nice to have estimated timetables but not a must.