I don’t think “logical fallacy” makes sense here. All arguments about reality incorporate unstated assumptions. Whether a vaccine is mandatory or not is determined by experts who weigh the benefit of the vaccine against the harms. I think @theophrastus’s comment assumes that if California is mandating the vaccine then it was determined to meet a threshold at which it should be mandatory. If that is true then they’d better make it mandatory or they do set a really ugly precedent.
There are probably people who believe that:
- the experts don’t actually know what they are talking about;
- data has been faked;
- this decision was political against the advice of true experts; and/or
- everything governments do is cynical and wrong
A person who believes any of that is going to disagree with the vaccine mandate, but not because of a logical fallacy in the argument for it, because they disagree about the nature of the reality that lead to it.