Good grief! No, it doesn't mean that, but what good does it do anyone to know that they once existed if we don't have them and therefore we have no idea what they actually SHOWED. It means there is NO PROOF of what they contained, and therefore no proof of the statements put forth by Blevins that there was a population replacement in the Peloponnese.
People, let's have some logic and common sense, shall we?
It's like Amber Heard constantly blathering about the mountains of evidence she has for her allegations, but the evidence was and is never produced, or if it's produced it's fragmentary, or the context is completely different from the one asserted, or the "evidence" is not an original document and so could have been altered.
You wouldn't even win in traffic court with this kind of reasoning, much less put together a population genetics paper.