As another archaeologist, I have to say that this is exactly the sort of thing that we find so darned frustrating. So many people don't really think of archaeology as a true science, and therefore tend to be willing to make arguements and leaps of faith that they wouldn't with any other science.

When it comes down to it, there are good archaeologists, and there are bad ones. Most of the bad ones are that way because they lack the proper training in the discipline. Instead, they are historians, religious studies people, or some other field, who think that sitting in on a dig makes them an expert. These are the people who make the wild leaps of faith that aren't soundly grounded in scientific theory and methodology. Good archaeology, done by good archaeologists, consists of logical conclusions based off of scientific data.

As to the two specific areas here, the Pyramids and the Tarim Basin mummies, here are my thoughts:

There is not one single shred of scientific evidence that says our dating system for the Pyramids is wrong. Therefore I see no reason to believe they date to 25kya, or whatever the number is. Until there is unquestionable scientific data otherwise, I'll continue to believe that.

The Tarim Basin mummies date to about 1000 BC. Not 10,000 BC. They seem to have features consistent with European features and European DNA patterns. Visually, they appear to be pale-skinned and red-haired. Their mummies, though. Coloration changes, and the fact that they appear to be pale-skinned and red-haired doesn't really mean much. The DNA is a much more telling feature. Of course, the fact that some Europeans happened to be in Western China in 1000 BC really isn't that big a deal. Trade routes existed, and there were Indo-Europeans all over the place.

So, can we be happy with this, until some genuine scientific data comes along that says otherwise?