Stephen,
Even if we may not see some things the same way, that's okay. I appreciate your input and all that you have shared. It is also what leads to critical thinking, and that's something everyone can use to do a bit more in life

.
Please know I am earnest in sharing this: If I could, I would turn back the hands of time and also would have asked my own group's lawyer to pursue DiStasio. He had encounters with him, as did I. It was not pleasant for any of us. And, maybe, just maybe: If more aggressive legal action had been taken from a civil standpoint, possibly DiStasio's "plan" might also have been thwarted.
Believe me: I take no comfort in any of this.
To me, this case is so much like ones where the suspected perps were reported, and the info. was totally solid but officers were maybe toking something stronger than DiStasio had in his stash. At this point, I have thought of asking those officers, but... I doubt they'd tell me. They might confide in a peer agent, however.
Officers are also following this thread and they know: I'm not a LE basher. They went through the same as I did with DiStasio and others. I wasn't trying to guess what might be probable cause. I mean, with S. Shurgard, heck, he filmed himself taking a box out of a closet (from a shelf) he self-labeled "child pornography." He posted it online. No one coerced him to do so no more than anyone knew DiStasio molested a toddler until he shared it.
It's just really discouraging to see some suggest folks are obsessed. No, we're not. We're trying to understand: Why federal officers, with over-riding jurisdiction, did squat. That hurts.
It's not easy doing this "stuff" tracking perps and reporting when cause is present, but to be considered obsessed or to suggest no lesson is to be learned (not that you have done so, since you have asked the question about what is the lesson) is like driving a stake into everything and saying: Kiss it off; he's in jail and let the chips fall where they may.
Not good enough. Maybe I'm hoping for answers no one can provide:
Why FBI turned a blind eye.
I could understand if I had cold-canvassed, but I was given the contact to FBI from a detective who vouched for me and the validity of my work.
So... where do parents turn when they ask for help and intervention from such an agency? That, to me, is another question.