agree, it is a slippery slope. On the other hand, though, what about these kids who are posting all over social media about their imminent plans to shoot up a school? Certainly identifying this person as someone who shouldn't be able to buy a gun is sensible?
I would be very wary of someone calling in and saying "*insert person* is a danger", and that alone being enough to prevent them from buying a gun or any other ramification for that person. But if they were looked into and there was clear evidence that such a claim was true, then someone calling in about it may have saved lives. If this sort of "call-in" approach were investigated by checking their social media and whatever else was sensible to check, I think i could do a lot of good.
The fact is that a lot of these mass shooters, we look at their social media after the fact, or in retrospect it turns out that many of their classmates had been trying to tell school officials or parents of their concerns, and we say "why didn't anyone do anything about this?" It's stuff like that where I think we should learn from these mistakes and implement some sort of system to make it easier to get reports like these into a system that would intervene, either by preventing gun sales, or involving police, before anything actually happens. I mean let's face it, if someone is posting all over social media that they plan to murder someone, or shoot up a school, that is nowhere near normal, and is really concerning, and should not be ignored. Likewise if someone is telling a bunch of their classmates they're going to kill them, that should not be ignored or trivialized.
I don't think of that as tattling or troubling, it's just sensible in the times we live in.
Back in my school days, we often received bomb threats from kids. Most all of the time, I'm sure it was just done to fuck with people or cause the rest of the school day to let out so they could skip class or something. But we always got evacuated, just in case. Of course, that was shortly after Columbine, back in the days before we had gotten desensitized to school shootings./mass killings.