He says there is no principled reason to ban spam, but there's an obvious one, it isn't really speech. The same goes for someone who posts the same opinion everywhere with no sense of contextual relevance. That's not real speech, it's just posting.
It's basically just public nuisance, like driving up and down a street blaring your favorite club banger at 3AM. More uncharitably its a lot like littering, public urination, or graffiti.
That's sort of what I mean. It's like putting up a billboard on someone else's property. Taking down the billboard isn't about the content of the billboard but rather the non-permitted use of the space.
