Spam is not speech. You haven't found a gotcha in the argument.

Spam is a form of harrassment.

If it's an attack, harrassment, violence, an initiation of force, etc. then it isn't speech. Which is why yelling "FIRE!" in a crowded theater is also not speech (despite people also thinking that's another gotcha example to free speech), it's an act of violence or attempted violence. Free speech doesn't exist in the context of violence being applied or threatened, an actor is not free if they're being threatened or attacked, they're under duress, which is a particular impingement of the mind.

> So it is censorship. We just all agree it's a good thing.

It's not censorship.