Maybe the tape actually rests on the head, see how the 8-9 inch appears shorter than the 7-8, like it's at an angle. You can actually see hints of shadows at the 9" mark when the tape (magically) gets straight again, and around the 7"1/4 mark where it would be suspended between the shaft and the head.
Anyway IMO the main shadows are the biggest issue here. First they are very, very dark. FWIW if you push the gamma enough that they're not pitch black anymore, they take on weird hues: reddish along the cock, yellowish along the tape, and greenish for the hand. I don't know how much of a red flag that is though. Then what's that gray bar between the hand and the cock that doesn't seem to be affected by the shadow? I can't explain it, it would have to be a strip of reflective material to look like this. I also don't like the way the tape's shadow hits that piece of furniture.
But then he's got a ruler pic showing the same measurement, and I can't see anything wrong with that one.