As Obama says "you can't vet the vetters..." right? So why try? The relevance is tht you have a guy running for President who continually gets caught up in lies about his past. Not the Jerimiah Wright he knew, etc. Let his grandmother vouch for him as you pointed out...wait, you'll have to get her out from under the bus first.
Better yet ask both candidates to prove it, maybe we can get a redo on both.