You've made interesting observations about the guarantee of freedom of speech (a more precise terms, as all people hold opinions, even when they live under despotic governments that outlaw certain speech).
You say that to hold a inequitable opinion, e.g. white supremacy, is tantamount to inequality itself. I disagree. In a democratic society based upon equality as encoded in the rule of law, individuals -- both official, e.g., policeman, and civil, e.g. the common man -- may act in unequal ways, but the remedy is not to stifle thought or speech, however reprehensible either might be, but to seek redress in a court of law. In other words, justice is blind. Now at this point you may be laughing cynically, but where the law is corrupt, as in courtrooms and judges which follow their own prejudices (or their paymasters), not the rule of law, that is not a fault of the system, but of the individual. The system of equality under the law remains a shining monument to humanity's struggle for freedom and justice for all.
You would somehow created equality before allowing for freedom. I think that both underestimates the ambiguity of the human heart, and opens the door for greater governmental abuse than we have now.
On a more philosophical note: we all have bad thoughts; sometimes, even evil thoughts. The difference between the good and bad person, however, is that the good person does not act on his evil thoughts.