He obviously believes in the pre-Clovis theory.
Yup. You mean with the Meadowcroft entry. He said that the North American results were a little 'murky' (my word), but, believes there were five different populations that entered from the north. The "X" gene came with one of those populations.
I was a little disappointed because he doesn't even mention a possible Atlantic entry to the Americas...apparently, it didn't show up in the DNA.
The "X' gene that is common to some Europeans and American Indians came through the previously mentioned routes from the north. He says the "X" gene link between Europe and the Americas was broken during the Toba explosion which, would mean that it is very ancient. He doesn't say it but, I'm guessing the "X" gene came with the Jomon/Ainu types like Kennewick Man/Spirit Cave man.