It's that but more than that. What is limestone composed of? What would/could a mortar contain? It sure woulndt be pure charcoal. Even wet or diluted it is not a bonding compound. Jon and others are not considering the elements that could throw off the results.
They also dont consider other dating context like the shafts poinring at known revered stars that only fit the mid 3rd milennium.
This group seems more Sitchin supporters than Hancock ones. I am sure these types of debates are not what Graham had in mind when this boatd was created.