It's assault. He should be tried for assault if Rock wants to press charges.
The Academy should not force Smith to return the Oscar. Horrible people win nice things all the time.
With BA2 and Omicron still running around, and the 2 years of isolation and stress, and his wife having alopecia, Smith's clearly quite brittle. The stress of being up for an Oscar or having just won it -- there's a heap of emotions in play. That's aside from any baggage from being a child star and Scientologist, as well as crazy rich.
Assault is never the answer to an insult. Even kings didn't kill the court jester.