How is "the earth is flat" not an opinion? People form opinions based on the information they have (or are willing to accept). For their worldview, their opinion is valid. If they don't accept certain voices of reason, they have that right. We saw people not allowed to ask about the origins of the covid19 virus because it went against a public narrative. At the beginning of the pandemic, people who expressed that masks should be worn were rejected by even government officials.

People might not have gone to jail, but they did have voices and access to society limited or removed because of their opinions.