This doesn't really have much to do with the scientific community except that fourth-tier journals can't always be counted on to conduct proper peer review.

No-one remotely familiar with either the anthropology or genetics of Mesoamerican cultures should have let this get past. The anthropology is possibly arguable, but the genetics really is not.

(And the story documents the other ways in which the paper falls below the minimum standards of scholarship needed to make a contribution to our understanding of the matter.)