The fact that you don't think the Harrison run was a touchdown makes me seriously question how objective you're being. I've not heard one non-Cardinals fan or Phoenix media member suggest it was even close to being short. I didn't even see a reply that showed his knee hit the ground short of the end zone.
YouTube - James Harrison 100 Yard INT TD
a look at this clearly shows that even if he was down on the initial hit and not on Fitzgerald's leg as another angle shows, the ball still appears to break the plane and therefore it's a touchdown.
Any argument is just silly.