Some things are categorically false, and those conclusions can be reached rationally. That seemed to be his only point, and he did not say anything about preventing anyone (like Carroll's Queen of Hearts) from believing six impossible things before breakfast. That would be authoritarian.

In a democracy like ours, stopping the Queen and others from enacting restrictive and harmful policy based on impossibilities only requires convincing arguments. People are still perfectly free to believe in Creationism, but convincing arguments have removed it from curricula.