We should ban any disinformation campaign that we as a society, through research and study, know to be a disinformation campaign.
We should ban any hypothetical authoritarian pro-trans party and their leaflets because they're an authoritarian party.
We shouldn't ban something for being woke because woke is now a fascist taking point to demonize the left and something being woke is not a real basis for something to be harmful.
There is a difference between personal mail and disinformation campaign leaflets. No one should be banning Christmas cards unless they are part of a targeted disinformation campaign to deny people the fundamental right to exist.
We as a society have chosen to leave this to individuals. This November 5th, the MAGA movement, a christo-fascist movement, is attempting to takeover our democracy. People in positions of leadership and power saying no to fascists attempting to subvert the results of the election may be all that stands between us and that christo-fascist takeover.
It would be better if there were systems in place to stop disinformation campaigns, but in this Canadian woman's case, her civil disobedience was the only system in place. We might soon find ourselves in her position. Where civil disobedience is the only recourse to prevent the worst outcomes of fascist policies. So we should not discount civil disobedience out of hand.
Also, fascists are bad-faith actors. Bad-faith actors will attempt to undermine our institutions for their gain no matter what we do. So our efforts should instead go to preventing bad-faith actors like fascists from taking power.
I am copying this here, because it's what refutes your argument's central point. We should not factor in what fascists will do into our decision making process. Fascists will try to destroy our way of life no matter what we do. So instead of worrying about trying to appease fascists, which has never worked, we should focus on keeping fascists out of power. If the fascists takeover our democracy, we aren't getting it back for free. So we should want individuals to engage in civil disobedience to prevent fascists from taking power and enacting their policies. To do otherwise would make us complicit in our own destruction.
Freedom of speech rests on the foundation of the truth. If we elevate lies to the level of the truth we will lose our freedom of speech. There is no utility in tolerating intolerance. In humoring a known disinformation campaign we do not dissuade the fascists, who are always looking to see what they can get away with. Nor do we safeguard our liberties, but instead lay the groundwork for them to be taken away. If we let the fascist decide what is true then it is the fascists who decide what we speak.
Changing an institution to improve the institution is constructive. Keeping an institution the same when its flaws will cause the institution to collapse is destructive.
Standing up to fascists doesn't make us fascists. Changing flawed institutions for the better is not the same as destroying them. The way things are is how we go here. Keeping them that way is how things will get worse.