Alternate angle shows that, after the buzzer sounded, Devin Booker walked over to the Clippers bench to taunt/gloat. The shove by Cousins followed shortly after:

Michael Wilbon: "I'm talking to players and coaches now, mostly in the West...Here's what players not just on the Rockets think, but OKC, Utah, Clippers...They think Houston is better than Golden State...But nobody wants to say it on the record" lmao

Mo Wagner Rookie year matched up with Kevin Durant he fouled me and without knowing it was him I turned and said You cant guard me Durant Draymond and Demarcus Cousins were at the free throw line box out talking shit to me while i was shooting 3 free throws I was so shook I made 13

Trevor Booker sneaks into the Cavs huddle

Gerald Henderson forces overtime with a tip in at the buzzer