There was actually a trial, before a jury, and the jury apparently made the finding that he didn't intend it as an actual factual statement.
Since we know, and the court had found, that Musk actually did make these Tweets and presumably other people saw them, and the plaintiff submitted an affidavit, which was uncontroverted, that the statements were false, and there is no evidence he did any research whatsoever as to the truth or falsity of them, it looks like the jury's determination was based on 3.
I.e. did the people who actually read these Tweets believe, as a result, that Unsworth was actually a pedophile. Statements like this are defamatory per se but that does not mean you automatically win your case. It does generally mean you can defeat a motion to dismiss or for summary judgment unless the context is so clear that they weren't meant as factual statements that there is nothing to determine for a jury.
So, in this case, Unsworth did get his trial. He just lost, presumably because they didn't feel he'd proven the audience actually even believed these statements to be factual in nature.
In this case, Unsworth presented his evidence, by affidavit, that the statements he was objecting to were in fact false and were clearly defamatory per se. And he got to go to trial.
Here's the court's ruling denying Musk's motion to dismiss: