It’s uncertain from what I have read whether they are truly isolated or not. But it is highly likely that isolation is, in the long run, not good for a people, unless somehow they are hermitically sealed into a sort of “human zoo”; something that’s not likely possible.
Some scholars maintain that tribes such as this are remnants of much larger tribes that inhabited the Precolumbian Amazon Basin. They did not, after all, spontaneously generate where they are; they came from somewhere. It is increasingly believed by anthropologists that both North and South America had massively greater Precolumbian populations than are recorded, but because human diseases introduced by Europeans and Africans proceeded well ahead of them; sometimes centuries ahead, native populations in many places were reduced to tiny remnants.
Those tiny remnants, it is believed, “went primitive”, not out of choice, but out of sheer poverty of means that frequently attends tiny populations.
It appears to be the case that the immune systems of Amerinds vs. Europeans, Asians and Africans are genetically different; more geared to parasites than to microbes.
There is really nothing judgmental to say about the phenomenon. Europeans, Asians and Africans had traded diseases among themselves for millenia, and accrued widespread immunity or resistance to microbial diseases. Amerinds, however, were likely descended from small groups that became isolated in the Americas hundreds of thousands of years ago. It was inevitable that sometime or other, some group of Europeans, Asians or Africans would land on the shores of the Americas and spread diseases to which the Amerinds had little defense. Likely, by now, exposed native Americans have acquired most immunities by simple survival of those with the most adaptable systems.
If all that is true, it is no kindness to attempt to isolate people such as these. Sooner or later, they will be exposed to Eurasian/African disease, if only by killing and eating some domestic hog gone feral. (The likely fate of the Mississippian cultures) I’m with the previous poster who opined that they should be introduced to at least some kind of medically supervised contact.