So, the use of potential lethal force is justified?
And sometimes the slightest use of force can be lethal. E.g. nudging someone, who trips and falls backwards, their head falling smack into a pointy protrusion on a rock or a metal railing.
Simply driving your car is “potentially lethal”.
Was it warranted in this case? Was Rice’s life in danger? The authorities who prosecuted Rice don’t think so. Rice has apologized for his actions, which are inexcusable except for a lunatic fringe who defend his actions.