To me a dive is where there's no contact and player still goes down.
What the Sunderland player did above is just theatrical, and exaggerated.
Choudhury puts his hand on him and slightly pulls him back. Not to say their player had to go down like that, but it's still a stupid risk to take from Choudhury. Another ref gives that and there's not really much we could moan about. We'd direct our anger to the ref but it's Hamza who gives the ref a choice to make.
Ref doesn't book him because he probably sees the contact but it's not enough to warrant a foul. Which is ironic because loads of us, myself included, were berating him all game for all the soft fouls he was giving saying it's a contact sport