It appears that the Maya were advanced in their development of cities and technology (P trait). One wonders if the "human sacrifice" including the ballgame using human skulls thought part of their culture was a type of punishment for breaking their laws given NPA theory assertions that NP types can be extreme in their enforcement and punishment roles. One also wonders if the practice of trying to shape their babies heads to be flat was a way to make their heads unlikely to be used as a ball.
As to whether the NP habitancy designation can shed light on why the culture went into decline, it may cast a vote toward aggressive attacks from outsiders instead of their own actions as the cause of their decline. That seems to continue today as Guatamalans appear to be victimized by gang violence more than some countries in the region? And the knowledge of their high frequency of P trait tends to make us forecast that the Guatamalans would be a dutiful addition to any society though they may adjust rather slowly.