I hope it comes to you as a viewer that my opinion is that Moctezuma was strangled. The loyal citizens of the Aztecs, who valued their emperor like their god, could not possibly stone him due to the fact that it’s completely opposing their lifestyle and tradition that had been maintained for hundreds of years. On the other hand, the Spanish are ruthless. If they had allowed for a festival, then ironically massacred all the Aztec dancers, there are no aspects that would stop them from harming the emperor when the Aztecs have rules. Since they had Moctezuma imprisoned, simply strangling him would not have been a rough task at all, compared to people throwing rocks into the sky and hoping that it successfully hits a person's head would be more