I'd just like to mention upfront that I hope the research into possibilities of use of geopolymer continues, I'm sure it will be found to be much more prevalent in antiquity than current thinking ascribes. There seems to be some basis in certain applications and places such as South America possibly, who knows.
This is not a post which is meant to sideline the geopolymer school of thought in ancient megalithic engineering/building. This is a quick synopsis of why it doesn't solve the primary mysteries of the anomalous works of stone, or the associated logistical and operational feats so obviously beyond the means attributed so unforgivably to the peoples of the time.
1) We have the quarries with the clear signatures of the biggest sites. Some, like those in Giza, have had specific blocks actually matched to the squares removed from bedrock quarries.
2) Some, like the unfinished obelisk of Aswan quarry, are still there, about two thirds completed.
3) Certain structures, like the pyramids, contain up to 2 million blocks and about 1.3 million are different shapes and sizes to each other. Making that many moulds seems to be more of a task almost than quarrying the granite in the first place.
4) Granite is very different to any form of concrete or polymer. Also each quarry produces different rock that can be linked definitively to megalithic construction sites.
5) No records for polymer industry on such scales exists and no associated tools.
6) The critical blocks have a variety of tooling marks on them, this is already a source of much debate in Egyptology VS Engineering (and Stonmasonry).
