If anything this gives the probablility of the Ark existing as much as the Great pyramids
Wrong. The probability of the Great Pyramids having existed is 100%. The probability of the ark having existed is much less.
Wrong. Perhaps in your opinion the probability of the ark's existence is much less. But that is based on a very unclear view of the Bible and of history. If what you know about the Bible were really all that we today could know about it and the accounts it contains, then your figuring would possibly be correct. The ark's probability would be considerably less. However your lack of understanding of the Bible's historical accuracy does not mean that the rest of us should see the ark's probability of existence as any less than that of the pyramids existence.
However I believe Chuck's point is that you can't use the fact that some think men in Noah's day didn't have the technological know-how to build the boat he built with the dimensions and requirements he had to adhere to to rule out its existence, since the pyramids show the use, thousands of years ago, of technology and geological understanding which is likely beyond that of modern man. There are other cases of colossally huge stones perfectly fitted together centuries ago which still exist and surpass the technical know-how of modern man (in South America).