this would be a real problem when an unknown sample falls too close to a known and one can't justify testing it further.
Sorry, but whoever pulls this one is standing on very shaky grounds. Be it from ignorance, be it from dishonesty, be it from bias, whatever is the source, the argument is flawed and it doesn't take a specialist on genetics to see that.
DNA tests are "razor-sharp" enough to distinguish between individuals; they can tell who are your parents, relatives and where your ancestors came from. They can separate genus, species and subspecies. If bigfoot existed, a good DNA assay would result, for example, in:
If bigfoot is related to Gigantopithecus:
Animalia, Chordata, Mammalia, Primate, Hominidae, Ponginae, unidentified genus
If bigfoot is, as some footers are now claiming, from our own genus:
Animalia, Chordata, Mammalia, Primates, Hominidae, Homo, unidentified species
DNA assays returning just "unknown" and/or "inconclusive" can not back bigfoot as a real critter; they only back bigfootery's methodologic incompetence. Sorry if it sounds harsh, but its the truth.