You should watch it again, or read the transcript. There was more high level messaging in there than you are giving Biden credit for. Yeah, he was declaring war in the sense that he was saying "bring it on." There was no more room for pussyfooting around on that in light of recent threats. But he was clearly telling the power center directors in the Trump movement that things have changed, blood has been shed, lines have been crossed, and we are in a Force Majeure type situation. He's telling you guys that the Dems won't hesitate to go on the offensive if the situational dynamics demand it, and that Trumpers need to watch their six. It's the nature of this situation, and it was bound to get bloody.
I think he gave a good performance, given where we are in this process. He's no Churchill, but he delivered the goods, and the Trump movement has a LOT to think about as they go further down this dangerous road. Blood for blood. It means what it means. That's what Biden was communicating.