Basically I think you are comparing quantum pure states with high entropy classical states with some assignment to all outcomes and concluding objectivity. Rather you should compare like with like. All quantum states with all classical states. Then you will see there is no difference.In contrast, other than 0 or 1 probabilities, no single observation can prove a Bayesian probability assignment wrong
Bayesian probability assignments which cover the whole sample space are analogous to mixed states in quantum mechanics, thus there is no difference. You shouldn't compare these to pure states.