Diamond makes too deterministic of an argument there, since it's ultimately a culture's need which determines what gets domesticated and what doesn't (although biological factors play a big role in things). I take Soviet experiments on foxes and moose to be illustrative of this--IIRC there's also been nice research on muskox in this context too. They created domesticated populations of those animals albeit using modern knowledge on breeding and not under the food constraints of what a Neolithic population would face (why domesticate an animal when you can just kill it?).
Take my example of aquatic agriculture involving wapato and
Zizania wild rice and no doubt fish farming. Using moose (as some water buffalo equivalent) would really help. So you could have these communities become closer to moose and subsequently domesticate them because now there's a need for it. Or if the Salish, who used mountain goat wool for various things, suddenly had a population boom (from some new sort of agriculture), they would have more people closer to where the mountain goats lived and a sudden demand for their wool. Although mountain goats can be aggressive, a less aggressive population might be cultivated and thus given a few centuries you have domesticated mountain goats.
I think of it as a cultural question, similar to how an alien anthropologist might ask why we're so worried about the dangers of fossil fuels now when we had solar panels since the late 19th century and nuclear power since the mid-20th. Culturally and economically, we didn't have a need for them, but if you examine our history, there's ways we might've been able to use them a lot more.
Which in of itself supposes that any of the number of American horse and camel species are domesticatible, or more precisely, that any Amerindian group actually has a need to domesticate them. Certainly a lot of people in the Old World had no need to domesticate the horse or other animals.
A West Coast trade network from Tierra del Fuego to the Aleutians would use both. Checking the internet, there's placer deposits of tin in the Alaska Panhandle, not far from where copper can be mined, in addition to those in the Yukon, Alaska Peninsula (near Bristol Bay) and Seward Peninsula which isn't far from copper deposits either. IOTL, both the Tlingit in the Alaska Panhandle and the Athabaskans along the Yukon traded for copper and used it to some degree, so an Alaskan Bronze Age isn't quite as ludicrous as it seems. Some agriculture is possible in Tlingit territory, and
this map suggests that
Sagittaria cuneata (wapato) grows as far north as the Mackenzie and Yukon Rivers, so potentially could be used for a slightly increased population density in the region (caribou herding and increased horticulturalism for the sake of humans and caribou both is also nice). In addition, trading for food from the south (Tlingit country, PNW, etc.) is always possible for any group involved in this. The poverty of the land for farming and yet its wealth from trade in tin, gold, and silver could lead to a Phoenician-like group forming there who would perhaps end up in Siberia (IIRC there is some tin there, but it might not be easily accessible) and from there, we might get a trade route going which eventually the East Asians would take interest in and hopefully try and take hold of themselves in a less violent manner than Europeans did (or at worst, be like the French, favouring some natives over others causing a lot of conflict, but not a lot of actual settlement).