I want to start out by saying that I really enjoy your posts and threads on these subjects and want to thank you for your efforts.
Dating, or rather, re-dating, is now an area of huge controversy. I’m sure you’re more than familiar with the Sphinx controversy.
Another thing Shoch mentioned is that Eastern Islanders themselves have no tradition of having carved the statues; “others” in remote antiquity had carved them.
The Easter Islanders were extensively studied in the 1950s and 1960s by Thor Heyerdahl, and they do (or at least did) know all about their own history, including how to carve the statues using the local materials, how they were moved, and what happened that made the process stop. The fact is, Schoch used to fit in better with the late TH than he did with Robert Bauval, and it's too bad that's no longer the case. Now he cherrypicks stuff to support whatever he's pushing in his latest book, IMHO. Heyerdahl first made the connection between the S American mainland (Tiahuanaco, as a matter of fact) and Rapa Nui, based on art and architecture. The earliest statues on the island are few but stylistically different, and resemble S American work (also he excavated thoe earlier work to reveal formerly unseen details).
Regarding the Great Sphinx, I've always found his work on that compelling, and still do. In a way, the abuse he's suffered for that freed hm to go hog wild in the fringe, and as I've been there for years, I empathize with him, but since he's a rigorously trained scientist, he should know when to pull up.