The entire point of "freedom of speech" is freedom of expression. Ongoing psy-ops from Russia and other parties to undermine US democracy are not what I would consider freedom of expression.
1) You could be wrong. Numerous examples exist throughout history regarding the wrong opinion turning out to the be the truth.
2) Knowing wrong opinions makes you have greater understanding of the correct ones.
3) Roughly the expression argument you mention.
https://www.armyupress.army.mil/Journals/Military-Review/Onl...