I think we are going around in circles here. What he wrote was that the megaphone can be taken away if it violates others' rights by drowning them out. That's the point.

Free speech is regulated all the time. Whether we like it or not. Cigarette ads are banned from TV despite the fact that smoking is legal. The right to free speech is not an absolute principle. You have to take account of KD's exception to the metaphor.

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"It signifies injustice of the king and of the rich against the masses... and deceptions. Because of this, depredation kills some, and poverty afflicts others" -- Flores Albumasaris