I’ll make one more try at stating this simply.
Mesirah is not a good thing. There is no debate on that. There are instances when it is mandatory – according to halacha. Yes, halacha mandates that we access the secular authorities. Contemporary Poskim have spoken about this openly, and their piskei halacha are available. So mesirah is a double edged sword. It is either ossur or it is a chiyuv.
To the believers of the narrative that it is always ossur, you have a few problems. First, that halacha says differently. Secondly, as noted by the Gedolei Haposkim, we lack the competence to assess the credibility of an accusation. We cannot jump and accept it is certain guilt, nor may we dismiss it. We need to see to it that these is an evaluation to determine the veracity of the report. I have yet to encounter a single Rav anywhere that has the training to accomplish this.
To IYK:
You suggested that the needs in this situation should override halacha. That is unnecessary. Halacha speaks to that, and our poskim who know all about mesirah have told mandated reporters to fulfill their professional responsibilities. I will follow their direction any day, and ignore the rantings of those who wish it wasn’t so. In summary, mesirah can be following halacha.