This is exactly what it comes down to.

"I'm a free speech absolutist. Twitter should allow free speech."

So we should allow spam bots shilling Bitcoin scams on every thread? "No, I obviously didn't mean that."

What about obvious phishing attempts promising Nigerian riches? "Those are obviously fake, and we need to keep users safe."

Hardcore pornography? "No, lots of children use the site. Those should be filtered out at least behind some kind of flag."

Explicit threats of violence? Blackmail? "No, all of that is obviously not allowed."

Should I be able to write a script to post a thousand Tweets a second? "No, that strains the infrastructure. There should be a rate limit."

So then we come back to a long list of rules for what should and shouldn't be allowed, and all the absolutism goes out of the window.