If someone wanted to do a talk on exoplanets but weren’t allowed to because they also had views on phrenology would that be cancelling? That’s a more accurate analogy than the one you’re giving.
I see the issue now. We have been so inundated with bad actors gaining traction through moderate means to push their extremist agendas that it is inevitable that some people are thought wrongly categorized.
I'm not sure there is a systematic solution to this, each individual must simply do this, appeal the decision to a higher public opinion authority.
