As I said in the other comment, the Aztecs do not figure into this, they were not hunter-gatherers. An Aztec slave empire is obviously not a hunter-gatherer band. Having a slave empire de facto means you're not a hunter gatherer any more.

There are no modern uncontacted hunter-gatherer bands to observe. The Sentinelese have everyone from local fishermen to American Christian fundamentalists invading their island. The bands in the Amazon are being murdered by miners. Modern people attacking and threatening the Sentilenese and getting a hostile response says little - if they were invading other islands, that would be a different story.