I don’t see the paradox. I don’t have to give you a megaphone, but if you have one, I’m not allowed to take it from you.

What’s the paradox there?

It's a curious analogy because in many contexts, use of a megaphone is quite abusive warranting confiscation.

If I attend a political rally and the speaker uses a megaphone, that's fine, I have consented to it's use.

However other places I have witnessed their use has questionable legality due to breach of the peace because the audience has not consented e.g. getting heckled when entering a University site or getting assailed by someone promoting their batshit Christian cult when trying to do some shopping. I don't think anyone would assume a universal right to make unwanted amplified noise.

I have always assumed the megaphone to be figurative: a platform for publication, reach on Twitter, media advertising, etc.