With DNA "evidence" like this, one would be hard pressed to obtain a conviction for a traffic ticket, let alone anything more.
Once we find the buried remains, and have identified them beyond a doubt, there will be time for such studies. Until then, this is more of a publicity stunt than real science.
While there are some fascinating examples of cultural claims being backed up by DNA, hard data must be available. When an African group claimed to be Jews, their DNA did show markers for the Cohen group.
For the G. Kahn theory to be validated, some DNA will be needed. So far, such DNA is, as Clements remarked, "Scarce, Almighty scarce."
Yes, I wonder where they got Genghis Khan's DNA, since he was buried in a mass grave.
I can get them DNA from Morris Kahn if they want.