I do not know MM's intentions in "verifying" this report from Mr. Haney but mine were to find out exact information that IBS never reported - not to discredit her. I was told that the tracked scent were only into the parking lot/alley way which only makes sense because that is where Tom would have exited the house if there were lots of cars in the front.
Why would cars in the front prevent him from walking out the front door? He didn't drive a car there.