Dan,
Just a minor disagreement. I think the use of the label "Chacoan" in this case, even if innocent, is at least a far poorer choice than the use of the word "Mojave" in ball pythons, for two reasons important to the argument here:
1) As you note, the Chacoan Plain is a specific geographic designation, where tegu's are found. It is therefore grossly misleading to potential buyers to label a tegu "Chacoan" which is not from that region. In the extreme, use of the term "Chacoan" would be of dubious integrity in a legal review if someone claimed they paid for a tegu of "Chacoan origins", based solely on the implications of the name, in that the buyer would have a case, and the seller a liability. I do not think the seller needed to actually "claim" it was from Chaco in order for it to be viewed as deceptive, whether intended or not, and on that point, I disagree with your take. An explanation would be required to keep it from being deceptive, intentions not mattering.
2) Secondly, and more importantly here, since it meant nothing to all the sellers regarding the actual origin of the "morph", if it is even that, in a peer sense it was fair game for anyone to pretty much use it as they saw fit. Bobby's argument was rooted in some sort of claim to the word "Chacoan" as he defined it, and he owned no such definition in any review, as others had applied it differently, and geographically incorrectly, before him. Which gets me back to my first point. Once the legal veracity of the term "Chacoan" became moot to all involved, they had no basis on which to claim any new meaning as proprietary.
For differing portions of both of the above arguments, it seems all parties have dropped it.
I think we're in 99% agreement on all things here anyway

.