Old Dog, M.K. Davis is not saying we know nothing for sure about Bigfoot. Exactly the opposite. There IS something we know for sure, in his view. He is saying that what we absolutely DO know for sure about Bigfoot is that Bigfoot is human, and not an ape. There is no leaning toward one or the other. For him, the record (the Patterson-Gimlin film) is 100% clear that Bigfoot is human.
He is trying to say, look at the evidence. Don't let scientists who are in search of fame and money fool you with their razzle-dazzle made-up stuff. That's all he's saying.
And OntarioSquatch, yeah, that's pretty much it. Although again, Davis is bothered by a very particular questionable concept. But yeah, I'm pretty much in agreement that everything on your list is dead wrong, except for the first one -- because, to be honest, I'm not really sure what a "relict hominid" is. If one of the implications of the label "relict hominid" is that there are few to zero individuals still here in current times, that's clearly wrong. But from what I understand, they are certainly hominids, and they are certainly more likely (according to Lloyd Pye) to have sprung from (or be more closely related to) all the beings we've been accustomed to claiming as our direct ancestors than we are.