The article is written in the typical uninformative half assed manner so the following is my interpretation of what the author and the caretaker are trying to say.
Erasers and power washing would result in the same damage that is the concern.
The pictures of moai we see generally appear to be naked rock and obviously grass fires dont damage basalt. What most people dont know and the author doesnt bother to explain is that these were once painted and traces of the paints are still on many of the moai.
Which parts were painted, why those parts were painted certain colors and what that means, what was used as pigment for those paints, etc, are all important to those continuing to study the moai. Soot would potentially burn off and stain out what is left of the paint on the exposed ones.
Yes, many are buried and much can be learned from those but as with any study of the past there can be changes in beliefs that would effect styles and methods over time that would lead researchers to be able to eventually better determine the phase in which each was made.
The loss of paint would then require even more guessing and interpretation on the part of researchers making it less factual and even more based on assumptions which is a problem in a field that is already based on a lot of SWAG and dogma.
I did not know that the statues had been painted. However, I don’t see the need to “power wash, etc” off the burn marks, eve if there were any remains of paint on them; and even more so to avoid with there being traces of 500+ year old paint.
Thank you for providing that crucial information about the paint ruined by the fire. It will be impossible to replace what was burned.