Graham himself debated an actual archeologist on the Rogan podcast not too long ago. I think he makes it pretty clear that he's mostly advocating that there is a nonzero amount of evidence for a pre ice age civilization that was significantly more advanced than immediate post ice age civilizations.

Im not convinced he's correct, but that doesn't make his stuff invalid. He's basically just presenting an alternative interpretation of the data and academic archeology is vilifying him for it, which they've done to several people before who ended up being right.

Of course in his shows he presents everything as fact, just like every other science does.