It is a bit of a special situation since the interfering was over a fake case, through the legal frame work of sting operations has always been a bit grey. It seems to me however that it flights clearly above that of first amendment rights. It seems simply that the prosecutor chose to go after CFAA because the case is about a sting case rather than a real one. Had the police officer interfered in a real case, where a criminal had been given information that obstructed police officers in their job, the case had been about that.
If that is true then the case has very little to do about internal policy decisions, exceeded permissions, unauthorized vs authorized users, employee contracts and so on. It is actually about sting operations and a prosecutor who attempts to bypass that discussion by using a law designed for a different purpose.
If you have insider information on an ongoing investigation and you tell it to your buddy at the bar who doesn't care one bit about it and immediately forgets, that's not obstruction of justice because the speech itself isn't the criminal act. If you tell that same information to the suspects though, then that's obstruction of justice.
With classified (natsec) information, on the other hand, telling it to anyone who you're not absolutely certain has clearance to see it is a violation and could land you in jail for years if you get a bloodthirsty DA. (again, IANAL)