I assume the sign is new? I don't remember it when we were there.
There seemed to be a mix of new and old signs around the island. New signs were at most of the more restored sites. There were also several more informal signs placed by Rapa Nui. The level of control over sites is below what similar archaeologically important sites elsewhere in the world generally have. There is a lot going on. We could have easily spent a couple weeks there soaking it all in.