Here the Real Parties in Interest are jumping into the fray. A Demurrer is a filing where the Respondents (or in this case the RPIs) say, even if all of the facts the Petitioner alleged are true, we didn’t break the law because the things the Petitioner alleges we did aren’t against the law.
It’s clever for the court to break the case up into these two parts. Arguing over facts is time consuming and expensive. If the judge can determine that no crime was committed even under the Petitioner’s version of the facts, then the parties & the court don’t have to waste resources arguing over the facts.