He took one, off-balance step toward Atiki as he was getting up, and then seemed to be turning to go up court right before impacting Atiki's elbow/forearm. It's not clear at all to me whether that first step was meant to be physically aggressive, just getting in his face (which is pretty common), or just him being off-balance.
I get that we can all interpret what happened differently. I disagree with other interpretations.