Yeah, his grip was fine. Thumb locked over the bar as opposed to under it, which I do sometimes for a variation. He made a serious mental error though, when he knew he was failing he dropped the weight and threw this hands up to complete the motion. Had he just allowed the fail to happen and laid the bar down on his chest, he would have been fine. I don't even think it slipped at all. It's tragic for sure. The spotter on the left was asleep at the wheel.Edit:no it was a regular grip...You have to look closely, plus I'm reading another thread about this.
Edit: Maybe it did slip after all, it's hard to tell. He definitely should have just laid the bar down once the struggle began. Better safe than sorry.