Society has already decided that proving guilt in a drunk driving case is a sufficient reason to violate bodily autonomy. I argue that saving a life is far more important than proving guilt for a fairly petty crime, therefore by the already accepted standard, it would be permissible to force the transfusion for this purpose.
But we haven't decided that saving the life of someone who's been endangered by your actions is an appropriate reason to violate bodily autonomy. That's the whole point, society has decided that you can refuse to give the transfusion, even it leads to a death you essentially caused.