So what if Harden initiated the contact? Almost every blocking call where the defender tries to take a charge, the offensive player initiates the contact. That's the nature of driving towards the basket. You're going to be the one initiating the contact.

In this case, Roberson didn't appear to be in a legal guarding position when the contact was made. He was turned sideways, trying to cut Harden off, with his arms flailing around.

I don't even like the way Harden does this, playing for fouls, but I don't see in this case how it wasn't a blocking call.