I have taken a pretty hard look at the question of pre-contact, north-south trade in the west and I can find no compelling evidence for northern Northwest Coast groups traveling south as far as California.

Following contact, fur traders quickly recognized the items of value to the natives and imported material like California (pink and red) abalone to the far northwest. My reading of the abstract of the article cited in support of the claim suggests that they are talking about evidence of California abalone in post-contact contexts.

Sticking just with Mexico and South America claims, they are garbage and an example of citation abuse on Wikipedia. Working backwards, the WP article says:

It is possible that the people of Haida Gwaii migrated to Mexico, Central America, and South America and that these people are closely genetically related.

Note this does not say that the Haida people migrated further into the Americas, just that people who first reached this island may have continued on. Since a coastal route in NW North America is one of the proposed routes for the peopling of the Americas, this is unremarkable, as is the notion that indigenous people in the Americas share a relatively close genetic ancestry, given the population bottleneck of Beringia. The citation also goes to apparently no longer extant article on a website for a commercial genetic testing company, not an academic article. This claim is meaningless fluff that has nothing to do with the actual Haida people.

The other claim is:

The Haida were skilled traders, with established trade links with their neighboring First Nations on the mainland to California and perhaps to Mexico’s Yucatán Peninsula.

/u/retarredroof roof has addressed the California bit, so I'll stick with the latter claim. The citation is about the debate over very early Americans (paleoindians) have somewhat different craniofacial skeletal features than what we consider the "classic" craniofacial characteristics of Native Americans. One hypothesis is that Paleoindians represent a separate, earlier migration into the Americas from Asia. The Science article focuses entirely on set of remains found in the Yucatan dated to around 12K years ago with Paleoindian traits but with a "classic" genetic signal to posit that "Paleoamericans represent an early population expansion out of Beringia, not an earlier migration from elsewhere in Eurasia."

Again, nothing about the actual Haida people, and certainly nothing about trade and contact between ethnic groups that would not even coalesce until thousands and thousands of years after the time frame being discussed in the article.