He's well within his right to mouth off at Pollard after beating him with a bouncer tbf.
Pollard made the first dick move by pulling away when Starc was just about to hit his delivery stride. I thought it was intentional but it could be debateable. However that definitely did not warrant hurling a ball at a 140ks at someone who had literally turned his back to him. If Pollard was hit or injured there Starc would be in deep ****. Pollard's reaction was uncalled for as well, if you say his bat slipped out of his hand and fell to the ground, what if it had slipped slightly earlier and hit Starc? Both of them basically lost their temper and did something stupid in the spur of the moment.
Personally thought it was pretty awesome and took perverse pleasure in watching it unfold
I don't think the IPL committee will mind it either because it'll definitely help generate hype and interest for this season at least. They're even cashing in on it by posting it on the Youtube channel with the title CRICKET FIGHT..