Just think of the Aztecs as being the "Mexican Taliban"
Well, they were evil, but that wasn't the reason they were ripe for the Spaniards to take down their culture. The real villain: a centralized economy.
Up until about four years before Cortes arrived, human sacrifice was an important part of Aztec religious ritual but, in terms of raw (pun intended)numbers, probably insignificant.
At this point, for reasons much open to debate, the imperial court began to usurp the functions of what we would call the middle class, re-directing the economy to one of tribute rather than trade and putting state resources into temple-building and wars intended to capture more sacrificial victims.
The government class literally ate the will of the populace to support it and, when Cortes arrived on the scene, there was no shortage of allies to bolster his ranks against Montezuma.
The moral: Cut people's hearts out all you like, but don't interfere with the business of trade trade and unfettered commerce that is a nation's greatest strength.
Also, this poster is taking the godless schools schtick a bit too far. Would he stop his kids joining a debating team, where your personal belief in the rightness or otherwise of the contention being debated is immaterial? Imagining yourself to be an Aztec priest justifying human sacrifice doesn't mean you have to agree with those human-skin covered priests atop their bloody pyramids, though attempting to do so might encourage using some of the grey matter schools generally prefer to leave undisturbed.
The jesuits, God bless 'em, have been doing this sort of thing for years (getting kids to play devil's advocate as an intellectual exercise) and it hasn't produced too many ex-pupils who go on to careers of tearing the beating hearts out of fellow citizens.
You'll notice, too, that the question gives students the option of imagining themselves to be a conquistador.
That said, the schools still suck -- mostly because the kids aren't challenged to think (because their teachers can't think, either)