40302 of the California Vehicle Code enumerates the circumstances under which an officer is required to arrest an individual and take him/her into custody. It says nothing about a right to refuse to sign a citation. In fact, quite the opposite, it states that an arrest is required when the individual is unlicensed, refuses to sign a citation, or insists on being arrested.
40302 (c) of the California Vehicle Code covers those circumstances where an individual demands to be arrested and taken before a magistrate. I saw no evidence of such a demand being made in this case.