If you are saying something is or probably is wrong, you have a burden.
Nope - it is critique of the claim being made (by Spud), and this critique says nothing about the claim being shown to be "wrong", which would be a positive claim, but simply points out that the claimant has failed to establish a robust verification for their claim, which implies that they haven't successfully demonstrated that their claim is factually correct: possibly because, as pointed out, there seems to be no basis for the independent verification of the ancient genealogies that are the subject of this particular claim.
Therefore that this claim might be incorrect remains a risk - and it is for the claimant (Spud) to address this risk, and if he can't then he'd surely have to concede that if the precise details are now unknowable, from this distance in time, then the account he has to hand cannot be substantiated, hence the risk that his claim may be incorrect. He can, of course, choose to believe it on a personal basis but he has no grounds to claim that what he believes is factually correct.
You've always struggled to understand what the burden of proof entails.