But his behavior, aggressive or intoxicated, should have no bearing on the 'disproportionate' response of Bryant: to try several times and in several different, increasingly dangerous methods, to severely injure and probably kill the cyclist.
If, as you say, Bryant used "increasingly" dangerous methods to try to dislodge Sheppard, that would actually be a point in his favour, yes? I mean, if he tried a less dangerous thing, and Sheppard hung on, and he tried a more dangerous thing, and Sheppard still hung on, I doubt the law would expect Bryant to have continued trying ineffectual methods of getting Sheppard to let go. His actions couldn't have been all that disproportionate if Sheppard wouldn't just let go.