The other players, especially those on the Warriors are what escalated the situation.
What happened between Hibbert & Lee happens often when two big men are defending each other with a lot of physicality. It usually turns into a couple shoves and/or elbows but it doesn't last that long and it's quickly diffused. But then Curry comes rushing in and grabs Hibbert when he should've just grabbed his own teammate and to make matters worse it's almost like he's trying to bearhug him, so Hibbert naturally gets on the defensive end and shoves Curry off of him. Make matters worse, you have Klay Thompson and surprise, surprise, that moron Jarrett Jack shoving Hibbert and other Pacers players into the crowd just exasperating the situation even more
Seriously though, Hibbert shouldn't have been suspended, even if it was only one game. Curry, Thompson, Jack, and anyone else that ran in and escalated the fight should be the ones that were suspended.
All Hibbert did was defend himself. Lee is out there throwing elbows at him and he responds, Curry bearhugs him and he pushes Curry off of him and the size difference between them made the shove look worse than it really was, and then you have Thompson, Jack and Biedrins shoving him into the crowd.
I'll give Curry a pass though since he had good intentions, he just went about it the wrong way and should've just grabbed Lee if he wanted to break up the fight. But Thompson, Jack & Biedrins all just escalated the situation.